redis是什么?
是完全開源免費的，用c語言編寫的，是一個單線程，高性能的（key/value）內存數據庫，基於內存運行並支持持久化的nosql數據庫
redis能干嘛？
主要是用來做緩存，但不僅僅只能做緩存，比如：redis的計數器生成分布式唯一主鍵，redis實現分布式鎖，隊列，會話緩存
redis的安裝(用的百度雲服務器,centos7.5版本)
下面是Redis5.0.5 Linux版本的下載地址
http://download.redis.io/releases/redis-5.0.5.tar.gz
我安裝在以下路徑下
cd /usr/local/java
解壓Redis
tar zxvf redis-5.0.5.tar.gz
刪除安裝包
rm -rf redis-5.0.5.tar.gz
重命名為redis
mv redis-5.0.5/ redis
進入文件目錄
cd redis/
上面的redis.conf文件就是Redis的核心配置文件
編譯redis
make
出現以下報錯
這是因為redis是c語言寫的,需要安裝gcc編譯器
yum install gcc-c++
安裝好gcc之后執行一下make distclean 因為前面make的時候它編譯了一些東西 要先把他們清掉
make distclean
重新編譯
make
編譯完成后安裝redis
make install
默認安裝在/usr/local/bin路徑下,看下
make install 默認安裝到/usr/local/bin 目錄下） 使用：如果需要指定安裝路徑，需要添加 PREFIX 參數,命令如下
make PREFIX=/usr/local/redis/ install
好,安裝成功,在根目錄創建redisConf文件夾,並存放redis.conf核心配置文件的備份
cp redis.conf /redisConf/
進入redis解壓目錄,編輯配置文件redis.conf
vim redis.conf
bind 配置 指定可以連接本實例Redis的ip 如果注釋（刪掉）則任意IP都可以連接,一般寫本機ip就可以了
bind 127.0.0.1
這里要注意不能使用外網ip,必須使用內網ip才能啟動redis
比如我用的百度雲服務器ip是
180.76.58.137
那我這里不能填這個ip,因為他是外網ip,會無法啟動redis,我們可以使用命令來查看該服務器的內網ip,如圖
上圖中的兩個ip地址均可以填入.我測試過都能正常啟動redis
這樣配置的時候說明任意ip都可以訪問,配合如下配置,可以使用windows客戶端訪問虛擬機安裝的redis
protected-mode保護模式配置:禁止外網訪問redis ,默認yes
它啟用的條件有兩個，第一是沒有使用bind，第二是沒有設置訪問密碼。也就是說,如果你配置了bind,那不管你怎么配置,都算不啟用
如果啟用了，比如注釋掉了bind 127.0.0.1，再訪問redis的時候是無法連接的
protected-mode yes
port 配置 指定Redis的端口,默認6379
port 6379
daemonize配置 是否以守護進程啟動 默認no
當狀態為no是,按Ctrl+c就會退出redis,所以我們改成yes,即在后台運行
daemonize yes
配置完成,保存退出.啟動redis
/usr/local/bin/redis-server ./redis.conf
查看redis進程是否啟動
ps -ef|grep redis
啟動成功,用Windows客戶端連接redis
好,安裝redis成功.
最后附上一份中文注釋的redis配置文件內容
# Redis configuration file example. # # Note that in order to read the configuration file, Redis must be # started with the file path as first argument: # # ./redis-server /path/to/redis.conf # Note on units: when memory size is needed, it is possible to specify # it in the usual form of 1k 5GB 4M and so forth: # 配置大小單位,開頭定義了一些基本的度量單位，只支持bytes，不支持bit 對大小寫不敏感 # 1k => 1000 bytes # 1kb => 1024 bytes # 1m => 1000000 bytes # 1mb => 1024*1024 bytes # 1g => 1000000000 bytes # 1gb => 1024*1024*1024 bytes # # units are case insensitive so 1GB 1Gb 1gB are all the same. ################################## INCLUDES ################################### # Include one or more other config files here. This is useful if you # have a standard template that goes to all Redis servers but also need # to customize a few per-server settings. Include files can include # other files, so use this wisely. # # Notice option "include" won't be rewritten by command "CONFIG REWRITE" # from admin or Redis Sentinel. Since Redis always uses the last processed # line as value of a configuration directive, you'd better put includes # at the beginning of this file to avoid overwriting config change at runtime. # # If instead you are interested in using includes to override configuration # options, it is better to use include as the last line. # 引入其他文件 # include /path/to/local.conf # include /path/to/other.conf ################################## MODULES ##################################### # Load modules at startup. If the server is not able to load modules # it will abort. It is possible to use multiple loadmodule directives. # # loadmodule /path/to/my_module.so # loadmodule /path/to/other_module.so ################################## NETWORK ##################################### # By default, if no "bind" configuration directive is specified, Redis listens # for connections from all the network interfaces available on the server. # It is possible to listen to just one or multiple selected interfaces using # the "bind" configuration directive, followed by one or more IP addresses. # # Examples: # # bind 192.168.1.100 10.0.0.1 # bind 127.0.0.1 ::1 # # ~~~ WARNING ~~~ If the computer running Redis is directly exposed to the # internet, binding to all the interfaces is dangerous and will expose the # instance to everybody on the internet. So by default we uncomment the # following bind directive, that will force Redis to listen only into # the IPv4 loopback interface address (this means Redis will be able to # accept connections only from clients running into the same computer it # is running). # # IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES # JUST COMMENT THE FOLLOWING LINE. # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # 綁定Ip 指定可以連接本實例Redis的ip 如果注釋（刪掉）則任意IP都可以連接,一般寫本機ip就可以了 bind 127.0.0.1 # Protected mode is a layer of security protection, in order to avoid that # Redis instances left open on the internet are accessed and exploited. # # When protected mode is on and if: # # 1) The server is not binding explicitly to a set of addresses using the # "bind" directive. # 2) No password is configured. # # The server only accepts connections from clients connecting from the # IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain # sockets. # # By default protected mode is enabled. You should disable it only if # you are sure you want clients from other hosts to connect to Redis # even if no authentication is configured, nor a specific set of interfaces # are explicitly listed using the "bind" directive. #禁止外網訪問redis，如果啟用了，即使注釋掉了bind 127.0.0.1，再訪問redisd時候還是無法連接的 #它啟用的條件有兩個，第一是沒有使用bind，第二是沒有設置訪問密碼。 protected-mode yes # Accept connections on the specified port, default is 6379 (IANA #815344). # If port 0 is specified Redis will not listen on a TCP socket. #指定Redis的端口 port 6379 # TCP listen() backlog. # # In high requests-per-second environments you need an high backlog in order # to avoid slow clients connections issues. Note that the Linux kernel # will silently truncate it to the value of /proc/sys/net/core/somaxconn so # make sure to raise both the value of somaxconn and tcp_max_syn_backlog # in order to get the desired effect. # 此參數確定了TCP連接中已完成隊列(完成三次握手之后)的長度， # 當然此值必須不大於Linux系統定義的/proc/sys/net/core/somaxconn值，默認是511， # 而Linux的默認參數值是128。當系統並發量大並且客戶端速度緩慢的時候，可以將這二個參數一起參考設定。 # 在高並發環境下你需要一個高backlog值來避免慢客戶端連接問題 tcp-backlog 511 # Unix socket. # # Specify the path for the Unix socket that will be used to listen for # incoming connections. There is no default, so Redis will not listen # on a unix socket when not specified. # # unixsocket /tmp/redis.sock # unixsocketperm 700 # Close the connection after a client is idle for N seconds (0 to disable) # 當客戶端閑置多長時間后關閉連接，如果指定為0，表示關閉該功能 timeout 0 # TCP keepalive. # # If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence # of communication. This is useful for two reasons: # # 1) Detect dead peers. # 2) Take the connection alive from the point of view of network # equipment in the middle. # # On Linux, the specified value (in seconds) is the period used to send ACKs. # Note that to close the connection the double of the time is needed. # On other kernels the period depends on the kernel configuration. # # A reasonable value for this option is 300 seconds, which is the new # Redis default starting with Redis 3.2.1. # 設置多長時間檢測死連接 單位為秒，如果設置為0，則不會進行Keepalive檢測 tcp-keepalive 300 ################################# GENERAL ##################################### # By default Redis does not run as a daemon. Use 'yes' if you need it. # Note that Redis will write a pid file in /var/run/redis.pid when daemonized. # 是否以守護進程啟動 daemonize no # If you run Redis from upstart or systemd, Redis can interact with your # supervision tree. Options: # supervised no - no supervision interaction # supervised upstart - signal upstart by putting Redis into SIGSTOP mode # supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET # supervised auto - detect upstart or systemd method based on # UPSTART_JOB or NOTIFY_SOCKET environment variables # Note: these supervision methods only signal "process is ready." # They do not enable continuous liveness pings back to your supervisor. #可以通過upstart和systemd管理Redis守護進程，這個參數是和具體的操作系統相關的。 supervised no # If a pid file is specified, Redis writes it where specified at startup # and removes it at exit. # # When the server runs non daemonized, no pid file is created if none is # specified in the configuration. When the server is daemonized, the pid file # is used even if not specified, defaulting to "/var/run/redis.pid". # # Creating a pid file is best effort: if Redis is not able to create it # nothing bad happens, the server will start and run normally. #當Redis以守護進程方式運行時，Redis默認會把pid寫入/var/run/redis.pid文件，可以通過pidfile指定 pidfile /var/run/redis_6379.pid # Specify the server verbosity level. # This can be one of: # debug (a lot of information, useful for development/testing) # verbose (many rarely useful info, but not a mess like the debug level) # notice (moderately verbose, what you want in production probably) # warning (only very important / critical messages are logged) #設置日志的級別 debug、verbose、notice、warning，默認為verbose loglevel notice # Specify the log file name. Also the empty string can be used to force # Redis to log on the standard output. Note that if you use standard # output for logging but daemonize, logs will be sent to /dev/null #日志文件的位置，當指定為空字符串時，為標准輸出，如果redis已守護進程模式運行，那么日志將會輸出到 /dev/null 。 logfile "" # To enable logging to the system logger, just set 'syslog-enabled' to yes, # and optionally update the other syslog parameters to suit your needs. # syslog-enabled no # Specify the syslog identity. # syslog-ident redis # Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7. # syslog-facility local0 # Set the number of databases. The default database is DB 0, you can select # a different one on a per-connection basis using SELECT <dbid> where # dbid is a number between 0 and 'databases'-1 # 設置數據庫的數目。默認的數據庫是DB 0 ，可以在每個連接上使用select <dbid> 命令選擇一個不同的數據庫，dbid是一個介於0到databases - 1 之間的數值。 databases 16 # By default Redis shows an ASCII art logo only when started to log to the # standard output and if the standard output is a TTY. Basically this means # that normally a logo is displayed only in interactive sessions. # # However it is possible to force the pre-4.0 behavior and always show a # ASCII art logo in startup logs by setting the following option to yes. always-show-logo yes ################################ SNAPSHOTTING ################################ # # Save the DB on disk: # # save <seconds> <changes> # # Will save the DB if both the given number of seconds and the given # number of write operations against the DB occurred. # # In the example below the behaviour will be to save: # after 900 sec (15 min) if at least 1 key changed # after 300 sec (5 min) if at least 10 keys changed # after 60 sec if at least 10000 keys changed # # Note: you can disable saving completely by commenting out all "save" lines. # # It is also possible to remove all the previously configured save # points by adding a save directive with a single empty string argument # like in the following example: # # save "" # 指定在多長時間內，有多少次更新操作，就將數據同步到數據文件，可以多個條件配合 # 這里表示900秒（15分鍾）內有1個更改，300秒（5分鍾）內有10個更改以及60秒內有10000個更改 # 如果想禁用RDB持久化的策略，只要不設置任何save指令，或者給save傳入一個空字符串參數也可以 save 900 1 save 300 10 save 60 1 # By default Redis will stop accepting writes if RDB snapshots are enabled # (at least one save point) and the latest background save failed. # This will make the user aware (in a hard way) that data is not persisting # on disk properly, otherwise chances are that no one will notice and some # disaster will happen. # # If the background saving process will start working again Redis will # automatically allow writes again. # # However if you have setup your proper monitoring of the Redis server # and persistence, you may want to disable this feature so that Redis will # continue to work as usual even if there are problems with disk, # permissions, and so forth. # 默認情況下，如果 redis 最后一次的后台保存失敗，redis 將停止接受寫操作，這樣以一種強硬的方式讓用戶知道數據不能正確的持久化到磁盤， # 否則就會沒人注意到災難的發生。 如果后台保存進程重新啟動工作了，redis 也將自動的允許寫操作。 # 如果配置成no，表示你不在乎數據不一致或者有其他的手段發現和控制 stop-writes-on-bgsave-error yes # Compress string objects using LZF when dump .rdb databases? # For default that's set to 'yes' as it's almost always a win. # If you want to save some CPU in the saving child set it to 'no' but # the dataset will likely be bigger if you have compressible values or keys. # 對於存儲到磁盤中的快照(rdb)，可以設置是否進行壓縮存儲。如果是的話，redis會采用 # LZF算法進行壓縮。如果你不想消耗CPU來進行壓縮的話，可以設置為關閉此功能 rdbcompression yes # Since version 5 of RDB a CRC64 checksum is placed at the end of the file. # This makes the format more resistant to corruption but there is a performance # hit to pay (around 10%) when saving and loading RDB files, so you can disable it # for maximum performances. # # RDB files created with checksum disabled have a checksum of zero that will # tell the loading code to skip the check. # 在存儲快照后，還可以讓redis使用CRC64算法來進行數據校驗，但是這樣做會增加大約 # 10%的性能消耗，如果希望獲取到最大的性能提升，可以關閉此功能 rdbchecksum yes # The filename where to dump the DB #rdb文件的名字。 dbfilename dump.rdb # The working directory. # # The DB will be written inside this directory, with the filename specified # above using the 'dbfilename' configuration directive. # # The Append Only File will also be created inside this directory. # # Note that you must specify a directory here, not a file name. # dbfilename文件存放目錄。必須是一個目錄，aof文件也會保存到該目錄下。 dir ./ ################################# REPLICATION ################################# # Master-Replica replication. Use replicaof to make a Redis instance a copy of # another Redis server. A few things to understand ASAP about Redis replication. # # +------------------+ +---------------+ # | Master | ---> | Replica | # | (receive writes) | | (exact copy) | # +------------------+ +---------------+ # # 1) Redis replication is asynchronous, but you can configure a master to # stop accepting writes if it appears to be not connected with at least # a given number of replicas. # 2) Redis replicas are able to perform a partial resynchronization with the # master if the replication link is lost for a relatively small amount of # time. You may want to configure the replication backlog size (see the next # sections of this file) with a sensible value depending on your needs. # 3) Replication is automatic and does not need user intervention. After a # network partition replicas automatically try to reconnect to masters # and resynchronize with them. #設置當本機為slave服務時，設置master服務的IP地址及端口，在Redis啟動時，它會自動從master進行數據同步 # replicaof <masterip> <masterport> # If the master is password protected (using the "requirepass" configuration # directive below) it is possible to tell the replica to authenticate before # starting the replication synchronization process, otherwise the master will # refuse the replica request. #當master服務設置了密碼保護時，slave服務連接master的密碼 # masterauth <master-password> # When a replica loses its connection with the master, or when the replication # is still in progress, the replica can act in two different ways: # # 1) if replica-serve-stale-data is set to 'yes' (the default) the replica will # still reply to client requests, possibly with out of date data, or the # data set may just be empty if this is the first synchronization. # # 2) if replica-serve-stale-data is set to 'no' the replica will reply with # an error "SYNC with master in progress" to all the kind of commands # but to INFO, replicaOF, AUTH, PING, SHUTDOWN, REPLCONF, ROLE, CONFIG, # SUBSCRIBE, UNSUBSCRIBE, PSUBSCRIBE, PUNSUBSCRIBE, PUBLISH, PUBSUB, # COMMAND, POST, HOST: and LATENCY. #當一個slave與master失去聯系時，或者復制正在進行的時候，slave應對請求的行為: #如果為 yes（默認值） ，slave 仍然會應答客戶端請求，但返回的數據可能是過時，或者數據可能是空的在第一次同步的時候 #如果為 no ，在你執行除了 info 和 salveof 之外的其他命令時，slave 都將返回一個 "SYNC with master in progress" 的錯誤。 replica-serve-stale-data yes # You can configure a replica instance to accept writes or not. Writing against # a replica instance may be useful to store some ephemeral data (because data # written on a replica will be easily deleted after resync with the master) but # may also cause problems if clients are writing to it because of a # misconfiguration. # # Since Redis 2.6 by default replicas are read-only. # # Note: read only replicas are not designed to be exposed to untrusted clients # on the internet. It's just a protection layer against misuse of the instance. # Still a read only replica exports by default all the administrative commands # such as CONFIG, DEBUG, and so forth. To a limited extent you can improve # security of read only replicas using 'rename-command' to shadow all the # administrative / dangerous commands. #設置slave是否是只讀的。從2.6版起，slave默認是只讀的。 replica-read-only yes # Replication SYNC strategy: disk or socket. # # ------------------------------------------------------- # WARNING: DISKLESS REPLICATION IS EXPERIMENTAL CURRENTLY # ------------------------------------------------------- # # New replicas and reconnecting replicas that are not able to continue the replication # process just receiving differences, need to do what is called a "full # synchronization". An RDB file is transmitted from the master to the replicas. # The transmission can happen in two different ways: # # 1) Disk-backed: The Redis master creates a new process that writes the RDB # file on disk. Later the file is transferred by the parent # process to the replicas incrementally. # 2) Diskless: The Redis master creates a new process that directly writes the # RDB file to replica sockets, without touching the disk at all. # # With disk-backed replication, while the RDB file is generated, more replicas # can be queued and served with the RDB file as soon as the current child producing # the RDB file finishes its work. With diskless replication instead once # the transfer starts, new replicas arriving will be queued and a new transfer # will start when the current one terminates. # # When diskless replication is used, the master waits a configurable amount of # time (in seconds) before starting the transfer in the hope that multiple replicas # will arrive and the transfer can be parallelized. # # With slow disks and fast (large bandwidth) networks, diskless replication # works better. # 主從數據復制是否使用無硬盤復制功能。 repl-diskless-sync no # When diskless replication is enabled, it is possible to configure the delay # the server waits in order to spawn the child that transfers the RDB via socket # to the replicas. # # This is important since once the transfer starts, it is not possible to serve # new replicas arriving, that will be queued for the next RDB transfer, so the server # waits a delay in order to let more replicas arrive. # # The delay is specified in seconds, and by default is 5 seconds. To disable # it entirely just set it to 0 seconds and the transfer will start ASAP. repl-diskless-sync-delay 5 # Replicas send PINGs to server in a predefined interval. It's possible to change # this interval with the repl_ping_replica_period option. The default value is 10 # seconds. # 指定slave定期ping master的周期，默認10秒鍾。 # repl-ping-replica-period 10 # The following option sets the replication timeout for: # # 1) Bulk transfer I/O during SYNC, from the point of view of replica. # 2) Master timeout from the point of view of replicas (data, pings). # 3) Replica timeout from the point of view of masters (REPLCONF ACK pings). # # It is important to make sure that this value is greater than the value # specified for repl-ping-replica-period otherwise a timeout will be detected # every time there is low traffic between the master and the replica. #設置主庫批量數據傳輸時間或者ping回復時間間隔，默認值是60秒 。 # repl-timeout 60 # Disable TCP_NODELAY on the replica socket after SYNC? # # If you select "yes" Redis will use a smaller number of TCP packets and # less bandwidth to send data to replicas. But this can add a delay for # the data to appear on the replica side, up to 40 milliseconds with # Linux kernels using a default configuration. # # If you select "no" the delay for data to appear on the replica side will # be reduced but more bandwidth will be used for replication. # # By default we optimize for low latency, but in very high traffic conditions # or when the master and replicas are many hops away, turning this to "yes" may # be a good idea. #指定向slave同步數據時，是否禁用socket的NO_DELAY選項。 #若配置為“yes”，則禁用NO_DELAY，則TCP協議棧會合並小包統一發送，這樣可以減少主從節點間的包數量並節省帶寬，但會增加數據同步到 slave的時間。 #若配置為“no”，表明啟用NO_DELAY，則TCP協議棧不會延遲小包的發送時機，這樣數據同步的延時會減少，但需要更大的帶寬。 #通常情況下，應該配置為no以降低同步延時，但在主從節點間網絡負載已經很高的情況下，可以配置為yes。 repl-disable-tcp-nodelay no # Set the replication backlog size. The backlog is a buffer that accumulates # replica data when replicas are disconnected for some time, so that when a replica # wants to reconnect again, often a full resync is not needed, but a partial # resync is enough, just passing the portion of data the replica missed while # disconnected. # # The bigger the replication backlog, the longer the time the replica can be # disconnected and later be able to perform a partial resynchronization. # # The backlog is only allocated once there is at least a replica connected. # 設置主從復制backlog容量大小。這個 backlog 是一個用來在 slaves 被斷開連接時存放 slave 數據的 buffer， # 所以當一個 slave 想要重新連接，通常不希望全部重新同步，只是部分同步就夠了，僅僅傳遞 slave 在斷開連接時丟失的這部分數據。 # 這個值越大，salve 可以斷開連接的時間就越長。 # repl-backlog-size 1mb # After a master has no longer connected replicas for some time, the backlog # will be freed. The following option configures the amount of seconds that # need to elapse, starting from the time the last replica disconnected, for # the backlog buffer to be freed. # # Note that replicas never free the backlog for timeout, since they may be # promoted to masters later, and should be able to correctly "partially # resynchronize" with the replicas: hence they should always accumulate backlog. # # A value of 0 means to never release the backlog. #配置當master和slave失去聯系多少秒之后，清空backlog釋放空間。當配置成0時，表示永遠不清空。 # repl-backlog-ttl 3600 # The replica priority is an integer number published by Redis in the INFO output. # It is used by Redis Sentinel in order to select a replica to promote into a # master if the master is no longer working correctly. # # A replica with a low priority number is considered better for promotion, so # for instance if there are three replicas with priority 10, 100, 25 Sentinel will # pick the one with priority 10, that is the lowest. # # However a special priority of 0 marks the replica as not able to perform the # role of master, so a replica with priority of 0 will never be selected by # Redis Sentinel for promotion. # # By default the priority is 100. #當 master 不能正常工作的時候，Redis Sentinel 會從 slaves 中選出一個新的 master，這個值越小，就越會被優先選中，但是如果是 0 ， 那是意味着這個 slave 不可能被選中。 默認優先級為 100。 replica-priority 100 # It is possible for a master to stop accepting writes if there are less than # N replicas connected, having a lag less or equal than M seconds. # # The N replicas need to be in "online" state. # # The lag in seconds, that must be <= the specified value, is calculated from # the last ping received from the replica, that is usually sent every second. # # This option does not GUARANTEE that N replicas will accept the write, but # will limit the window of exposure for lost writes in case not enough replicas # are available, to the specified number of seconds. # # For example to require at least 3 replicas with a lag <= 10 seconds use: # # min-replicas-to-write 3 # min-replicas-max-lag 10 # # Setting one or the other to 0 disables the feature. # # By default min-replicas-to-write is set to 0 (feature disabled) and # min-replicas-max-lag is set to 10. # A Redis master is able to list the address and port of the attached # replicas in different ways. For example the "INFO replication" section # offers this information, which is used, among other tools, by # Redis Sentinel in order to discover replica instances. # Another place where this info is available is in the output of the # "ROLE" command of a master. # # The listed IP and address normally reported by a replica is obtained # in the following way: # # IP: The address is auto detected by checking the peer address # of the socket used by the replica to connect with the master. # # Port: The port is communicated by the replica during the replication # handshake, and is normally the port that the replica is using to # listen for connections. # # However when port forwarding or Network Address Translation (NAT) is # used, the replica may be actually reachable via different IP and port # pairs. The following two options can be used by a replica in order to # report to its master a specific set of IP and port, so that both INFO # and ROLE will report those values. # # There is no need to use both the options if you need to override just # the port or the IP address. # # replica-announce-ip 5.5.5.5 # replica-announce-port 1234 ################################## SECURITY ################################### # Require clients to issue AUTH <PASSWORD> before processing any other # commands. This might be useful in environments in which you do not trust # others with access to the host running redis-server. # # This should stay commented out for backward compatibility and because most # people do not need auth (e.g. they run their own servers). # # Warning: since Redis is pretty fast an outside user can try up to # 150k passwords per second against a good box. This means that you should # use a very strong password otherwise it will be very easy to break. # 設置Redis連接密碼，如果配置了連接密碼，客戶端在連接Redis時需要通過AUTH <password>命令提供密碼，默認關閉 # requirepass foobared # Command renaming. # # It is possible to change the name of dangerous commands in a shared # environment. For instance the CONFIG command may be renamed into something # hard to guess so that it will still be available for internal-use tools # but not available for general clients. # # Example: # # rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52 # # It is also possible to completely kill a command by renaming it into # an empty string: # # rename-command CONFIG "" # # Please note that changing the name of commands that are logged into the # AOF file or transmitted to replicas may cause problems. ################################### CLIENTS #################################### # Set the max number of connected clients at the same time. By default # this limit is set to 10000 clients, however if the Redis server is not # able to configure the process file limit to allow for the specified limit # the max number of allowed clients is set to the current file limit # minus 32 (as Redis reserves a few file descriptors for internal uses). # # Once the limit is reached Redis will close all the new connections sending # an error 'max number of clients reached'. #設置同一時間最大客戶端連接數，Redis可以同時打開的客戶端連接數為Redis進程可以打開的最大文件描述符數， #如果設置 maxclients 0，表示不作限制。當客戶端連接數到達限制時，Redis會關閉新的連接並向客戶端返回max number of clients reached錯誤信息 # maxclients 10000 ############################## MEMORY MANAGEMENT ################################ # Set a memory usage limit to the specified amount of bytes. # When the memory limit is reached Redis will try to remove keys # according to the eviction policy selected (see maxmemory-policy). # # If Redis can't remove keys according to the policy, or if the policy is # set to 'noeviction', Redis will start to reply with errors to commands # that would use more memory, like SET, LPUSH, and so on, and will continue # to reply to read-only commands like GET. # # This option is usually useful when using Redis as an LRU or LFU cache, or to # set a hard memory limit for an instance (using the 'noeviction' policy). # # WARNING: If you have replicas attached to an instance with maxmemory on, # the size of the output buffers needed to feed the replicas are subtracted # from the used memory count, so that network problems / resyncs will # not trigger a loop where keys are evicted, and in turn the output # buffer of replicas is full with DELs of keys evicted triggering the deletion # of more keys, and so forth until the database is completely emptied. # # In short... if you have replicas attached it is suggested that you set a lower # limit for maxmemory so that there is some free RAM on the system for replica # output buffers (but this is not needed if the policy is 'noeviction'). # 指定Redis最大內存限制，Redis在啟動時會把數據加載到內存中，達到最大內存后，Redis會先嘗試清除已到期或即將到期的Key， # 當此方法處理后，仍然到達最大內存設置，將無法再進行寫入操作，但仍然可以進行讀取操作。 # Redis新的vm機制，會把Key存放內存，Value會存放在swap區 # maxmemory <bytes> # MAXMEMORY POLICY: how Redis will select what to remove when maxmemory # is reached. You can select among five behaviors: # # volatile-lru -> Evict using approximated LRU among the keys with an expire set. # allkeys-lru -> Evict any key using approximated LRU. # volatile-lfu -> Evict using approximated LFU among the keys with an expire set. # allkeys-lfu -> Evict any key using approximated LFU. # volatile-random -> Remove a random key among the ones with an expire set. # allkeys-random -> Remove a random key, any key. # volatile-ttl -> Remove the key with the nearest expire time (minor TTL) # noeviction -> Don't evict anything, just return an error on write operations. # # LRU means Least Recently Used # LFU means Least Frequently Used # # Both LRU, LFU and volatile-ttl are implemented using approximated # randomized algorithms. # # Note: with any of the above policies, Redis will return an error on write # operations, when there are no suitable keys for eviction. # # At the date of writing these commands are: set setnx setex syc # incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd # sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby # zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby # getset mset msetnx exec sort # # The default is: #當內存使用達到最大值時，redis使用的清除策略。有以下幾種可以選擇（明明有6種，官方配置文件里卻說有5種可以選擇？）： # 1）volatile-lru 利用LRU算法移除設置過過期時間的key (LRU:最近使用 Least Recently Used ) # 2）allkeys-lru 利用LRU算法移除任何key # 3）volatile-random 移除設置過過期時間的隨機key # 4）allkeys-random 移除隨機key # 5）volatile-ttl 移除即將過期的key(minor TTL) # 6）noeviction 不移除任何key，只是返回一個寫錯誤 。默認選項 # maxmemory-policy noeviction # LRU, LFU and minimal TTL algorithms are not precise algorithms but approximated # algorithms (in order to save memory), so you can tune it for speed or # accuracy. For default Redis will check five keys and pick the one that was # used less recently, you can change the sample size using the following # configuration directive. # # The default of 5 produces good enough results. 10 Approximates very closely # true LRU but costs more CPU. 3 is faster but not very accurate. # LRU 和 minimal TTL 算法都不是精准的算法，但是相對精確的算法(為了節省內存)，隨意你可以選擇樣本大小進行檢測。redis默認選擇5個樣本進行檢測，你可以通過maxmemory-samples進行設置樣本數。 # maxmemory-samples 5 # Starting from Redis 5, by default a replica will ignore its maxmemory setting # (unless it is promoted to master after a failover or manually). It means # that the eviction of keys will be just handled by the master, sending the # DEL commands to the replica as keys evict in the master side. # # This behavior ensures that masters and replicas stay consistent, and is usually # what you want, however if your replica is writable, or you want the replica to have # a different memory setting, and you are sure all the writes performed to the # replica are idempotent, then you may change this default (but be sure to understand # what you are doing). # # Note that since the replica by default does not evict, it may end using more # memory than the one set via maxmemory (there are certain buffers that may # be larger on the replica, or data structures may sometimes take more memory and so # forth). So make sure you monitor your replicas and make sure they have enough # memory to never hit a real out-of-memory condition before the master hits # the configured maxmemory setting. # # replica-ignore-maxmemory yes ############################# LAZY FREEING #################################### # Redis has two primitives to delete keys. One is called DEL and is a blocking # deletion of the object. It means that the server stops processing new commands # in order to reclaim all the memory associated with an object in a synchronous # way. If the key deleted is associated with a small object, the time needed # in order to execute the DEL command is very small and comparable to most other # O(1) or O(log_N) commands in Redis. However if the key is associated with an # aggregated value containing millions of elements, the server can block for # a long time (even seconds) in order to complete the operation. # # For the above reasons Redis also offers non blocking deletion primitives # such as UNLINK (non blocking DEL) and the ASYNC option of FLUSHALL and # FLUSHDB commands, in order to reclaim memory in background. Those commands # are executed in constant time. Another thread will incrementally free the # object in the background as fast as possible. # # DEL, UNLINK and ASYNC option of FLUSHALL and FLUSHDB are user-controlled. # It's up to the design of the application to understand when it is a good # idea to use one or the other. However the Redis server sometimes has to # delete keys or flush the whole database as a side effect of other operations. # Specifically Redis deletes objects independently of a user call in the # following scenarios: # # 1) On eviction, because of the maxmemory and maxmemory policy configurations, # in order to make room for new data, without going over the specified # memory limit. # 2) Because of expire: when a key with an associated time to live (see the # EXPIRE command) must be deleted from memory. # 3) Because of a side effect of a command that stores data on a key that may # already exist. For example the RENAME command may delete the old key # content when it is replaced with another one. Similarly SUNIONSTORE # or SORT with STORE option may delete existing keys. The SET command # itself removes any old content of the specified key in order to replace # it with the specified string. # 4) During replication, when a replica performs a full resynchronization with # its master, the content of the whole database is removed in order to # load the RDB file just transferred. # # In all the above cases the default is to delete objects in a blocking way, # like if DEL was called. However you can configure each case specifically # in order to instead release memory in a non-blocking way like if UNLINK # was called, using the following configuration directives: lazyfree-lazy-eviction no lazyfree-lazy-expire no lazyfree-lazy-server-del no replica-lazy-flush no ############################## APPEND ONLY MODE ############################### # By default Redis asynchronously dumps the dataset on disk. This mode is # good enough in many applications, but an issue with the Redis process or # a power outage may result into a few minutes of writes lost (depending on # the configured save points). # # The Append Only File is an alternative persistence mode that provides # much better durability. For instance using the default data fsync policy # (see later in the config file) Redis can lose just one second of writes in a # dramatic event like a server power outage, or a single write if something # wrong with the Redis process itself happens, but the operating system is # still running correctly. # # AOF and RDB persistence can be enabled at the same time without problems. # If the AOF is enabled on startup Redis will load the AOF, that is the file # with the better durability guarantees. # # Please check http://redis.io/topics/persistence for more information. # 是否啟用aof持久化方式 。否在每次更新操作后進行日志記錄，Redis在默認情況下是異步的把數據寫入磁盤，如果不開啟，可能會在斷電時導致一段時間內的數據丟失。 # 因為 redis本身同步數據文件是按上面save條件來同步的，所以有的數據會在一段時間內只存在於內存中。默認為no appendonly no # The name of the append only file (default: "appendonly.aof") # 指定更新日志（aof）文件名，默認為appendonly.aof appendfilename "appendonly.aof" # The fsync() call tells the Operating System to actually write data on disk # instead of waiting for more data in the output buffer. Some OS will really flush # data on disk, some other OS will just try to do it ASAP. # # Redis supports three different modes: # # no: don't fsync, just let the OS flush the data when it wants. Faster. # always: fsync after every write to the append only log. Slow, Safest. # everysec: fsync only one time every second. Compromise. # # The default is "everysec", as that's usually the right compromise between # speed and data safety. It's up to you to understand if you can relax this to # "no" that will let the operating system flush the output buffer when # it wants, for better performances (but if you can live with the idea of # some data loss consider the default persistence mode that's snapshotting), # or on the contrary, use "always" that's very slow but a bit safer than # everysec. # # More details please check the following article: # http://antirez.com/post/redis-persistence-demystified.html # # If unsure, use "everysec". #指定更新日志條件，共有3個可選值： # no：表示等操作系統進行數據緩存同步到磁盤（快，持久化沒保證） # always：同步持久化，每次發生數據變更時，立即記錄到磁盤（慢，安全） # everysec：表示每秒同步一次（默認值,很快，但可能會丟失一秒以內的數據） # appendfsync always appendfsync everysec # appendfsync no # When the AOF fsync policy is set to always or everysec, and a background # saving process (a background save or AOF log background rewriting) is # performing a lot of I/O against the disk, in some Linux configurations # Redis may block too long on the fsync() call. Note that there is no fix for # this currently, as even performing fsync in a different thread will block # our synchronous write(2) call. # # In order to mitigate this problem it's possible to use the following option # that will prevent fsync() from being called in the main process while a # BGSAVE or BGREWRITEAOF is in progress. # # This means that while another child is saving, the durability of Redis is # the same as "appendfsync none". In practical terms, this means that it is # possible to lose up to 30 seconds of log in the worst scenario (with the # default Linux settings). # # If you have latency problems turn this to "yes". Otherwise leave it as # "no" that is the safest pick from the point of view of durability. # 指定是否在后台aof文件rewrite期間調用fsync，默認為no，表示要調用fsync（無論后台是否有子進程在刷盤）。 # Redis在后台寫RDB文件或重寫AOF文件期間會存在大量磁盤IO，此時，在某些linux系統中，調用fsync可能會阻塞。 #如果應用系統無法忍受延遲，而可以容忍少量的數據丟失，則設置為yes。如果應用系統無法忍受數據丟失，則設置為no。 no-appendfsync-on-rewrite no # Automatic rewrite of the append only file. # Redis is able to automatically rewrite the log file implicitly calling # BGREWRITEAOF when the AOF log size grows by the specified percentage. # # This is how it works: Redis remembers the size of the AOF file after the # latest rewrite (if no rewrite has happened since the restart, the size of # the AOF at startup is used). # # This base size is compared to the current size. If the current size is # bigger than the specified percentage, the rewrite is triggered. Also # you need to specify a minimal size for the AOF file to be rewritten, this # is useful to avoid rewriting the AOF file even if the percentage increase # is reached but it is still pretty small. # # Specify a percentage of zero in order to disable the automatic AOF # rewrite feature. #當AOF文件增長到一定大小的時候Redis能夠調用 BGREWRITEAOF 對日志文件進行重寫 。當AOF文件大小的增長率大於該配置項時自動開啟重寫。 auto-aof-rewrite-percentage 100 #當AOF文件增長到一定大小的時候Redis能夠調用 BGREWRITEAOF 對日志文件進行重寫 。當AOF文件大小大於該配置項時自動開啟重寫 auto-aof-rewrite-min-size 64mb # An AOF file may be found to be truncated at the end during the Redis # startup process, when the AOF data gets loaded back into memory. # This may happen when the system where Redis is running # crashes, especially when an ext4 filesystem is mounted without the # data=ordered option (however this can't happen when Redis itself # crashes or aborts but the operating system still works correctly). # # Redis can either exit with an error when this happens, or load as much # data as possible (the default now) and start if the AOF file is found # to be truncated at the end. The following option controls this behavior. # # If aof-load-truncated is set to yes, a truncated AOF file is loaded and # the Redis server starts emitting a log to inform the user of the event. # Otherwise if the option is set to no, the server aborts with an error # and refuses to start. When the option is set to no, the user requires # to fix the AOF file using the "redis-check-aof" utility before to restart # the server. # # Note that if the AOF file will be found to be corrupted in the middle # the server will still exit with an error. This option only applies when # Redis will try to read more data from the AOF file but not enough bytes # will be found. #redis在啟動時可以加載被截斷的AOF文件，而不需要先執行redis-check-aof 工具。 aof-load-truncated yes # When rewriting the AOF file, Redis is able to use an RDB preamble in the # AOF file for faster rewrites and recoveries. When this option is turned # on the rewritten AOF file is composed of two different stanzas: # # [RDB file][AOF tail] # # When loading Redis recognizes that the AOF file starts with the "REDIS" # string and loads the prefixed RDB file, and continues loading the AOF # tail. #是否開啟混合持久化 aof-use-rdb-preamble yes ################################ LUA SCRIPTING ############################### # Max execution time of a Lua script in milliseconds. # # If the maximum execution time is reached Redis will log that a script is # still in execution after the maximum allowed time and will start to # reply to queries with an error. # # When a long running script exceeds the maximum execution time only the # SCRIPT KILL and SHUTDOWN NOSAVE commands are available. The first can be # used to stop a script that did not yet called write commands. The second # is the only way to shut down the server in the case a write command was # already issued by the script but the user doesn't want to wait for the natural # termination of the script. # # Set it to 0 or a negative value for unlimited execution without warnings. #一個Lua腳本最長的執行時間，單位為毫秒，如果為0或負數表示無限執行時間 lua-time-limit 5000 ################################ REDIS CLUSTER ############################### # # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ # WARNING EXPERIMENTAL: Redis Cluster is considered to be stable code, however # in order to mark it as "mature" we need to wait for a non trivial percentage # of users to deploy it in production. # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ # # Normal Redis instances can't be part of a Redis Cluster; only nodes that are # started as cluster nodes can. In order to start a Redis instance as a # cluster node enable the cluster support uncommenting the following: # 是否開啟cluster集群模式 如果配置yes則開啟集群功能，此redis實例作為集群的一個節點，否則，它是一個普通的單一的redis實例。 # cluster-enabled yes # Every cluster node has a cluster configuration file. This file is not # intended to be edited by hand. It is created and updated by Redis nodes. # Every Redis Cluster node requires a different cluster configuration file. # Make sure that instances running in the same system do not have # overlapping cluster configuration file names. #雖然此配置的名字叫"集群配置文件"，但是此配置文件不能人工編輯，它是集群節點自動維護的文件， #主要用於記錄集群中有哪些節點、他們的狀態以及一些持久化參數等，方便在重啟時恢復這些狀態。通常是在收到請求之后這個文件就會被更新。 # cluster-config-file nodes-6379.conf # Cluster node timeout is the amount of milliseconds a node must be unreachable # for it to be considered in failure state. # Most other internal time limits are multiple of the node timeout. #這是集群中的節點能夠失聯的最大時間，超過這個時間，該節點就會被認為故障。如果主節點超過這個時間還是不可達，則用它的從節點將啟動故障遷移，升級成主節點。 # cluster-node-timeout 15000 # A replica of a failing master will avoid to start a failover if its data # looks too old. # # There is no simple way for a replica to actually have an exact measure of # its "data age", so the following two checks are performed: # # 1) If there are multiple replicas able to failover, they exchange messages # in order to try to give an advantage to the replica with the best # replication offset (more data from the master processed). # Replicas will try to get their rank by offset, and apply to the start # of the failover a delay proportional to their rank. # # 2) Every single replica computes the time of the last interaction with # its master. This can be the last ping or command received (if the master # is still in the "connected" state), or the time that elapsed since the # disconnection with the master (if the replication link is currently down). # If the last interaction is too old, the replica will not try to failover # at all. # # The point "2" can be tuned by user. Specifically a replica will not perform # the failover if, since the last interaction with the master, the time # elapsed is greater than: # # (node-timeout * replica-validity-factor) + repl-ping-replica-period # # So for example if node-timeout is 30 seconds, and the replica-validity-factor # is 10, and assuming a default repl-ping-replica-period of 10 seconds, the # replica will not try to failover if it was not able to talk with the master # for longer than 310 seconds. # # A large replica-validity-factor may allow replicas with too old data to failover # a master, while a too small value may prevent the cluster from being able to # elect a replica at all. # # For maximum availability, it is possible to set the replica-validity-factor # to a value of 0, which means, that replicas will always try to failover the # master regardless of the last time they interacted with the master. # (However they'll always try to apply a delay proportional to their # offset rank). # # Zero is the only value able to guarantee that when all the partitions heal # the cluster will always be able to continue. #如果設置成０，則無論從節點與主節點失聯多久，從節點都會嘗試升級成主節點。 #如果設置成正數，則cluster-node-timeout乘以cluster-slave-validity-factor得到的時間，是從節點與主節點失聯后， #此從節點數據有效的最長時間，超過這個時間，從節點不會啟動故障遷移。 #假設cluster-node-timeout=5，cluster-slave-validity-factor=10，則如果從節點跟主節點失聯超過50秒，此從節點不能成為主節點。 #注意，如果此參數配置為非0，將可能出現由於某主節點失聯卻沒有從節點能頂上的情況，從而導致集群不能正常工作， #在這種情況下，只有等到原來的主節點重新回歸到集群，集群才恢復運作。 # cluster-replica-validity-factor 10 # Cluster replicas are able to migrate to orphaned masters, that are masters # that are left without working replicas. This improves the cluster ability # to resist to failures as otherwise an orphaned master can't be failed over # in case of failure if it has no working replicas. # # Replicas migrate to orphaned masters only if there are still at least a # given number of other working replicas for their old master. This number # is the "migration barrier". A migration barrier of 1 means that a replica # will migrate only if there is at least 1 other working replica for its master # and so forth. It usually reflects the number of replicas you want for every # master in your cluster. # # Default is 1 (replicas migrate only if their masters remain with at least # one replica). To disable migration just set it to a very large value. # A value of 0 can be set but is useful only for debugging and dangerous # in production. #master的slave數量大於該值，slave才能遷移到其他孤立master上，如這個參數若被設為2，那么只有當一個主節點擁有2 個可工作的從節點時，它的一個從節點會嘗試遷移。 #不建議設置為0 #想禁用可以設置一個非常大的值 #如果小於0則啟動失敗 # cluster-migration-barrier 1 # By default Redis Cluster nodes stop accepting queries if they detect there # is at least an hash slot uncovered (no available node is serving it). # This way if the cluster is partially down (for example a range of hash slots # are no longer covered) all the cluster becomes, eventually, unavailable. # It automatically returns available as soon as all the slots are covered again. # # However sometimes you want the subset of the cluster which is working, # to continue to accept queries for the part of the key space that is still # covered. In order to do so, just set the cluster-require-full-coverage # option to no. # 表示當負責一個插槽的主庫下線且沒有相應的從庫進行故障恢復時，是否整個集群不可用？ # cluster-require-full-coverage yes # This option, when set to yes, prevents replicas from trying to failover its # master during master failures. However the master can still perform a # manual failover, if forced to do so. # # This is useful in different scenarios, especially in the case of multiple # data center operations, where we want one side to never be promoted if not # in the case of a total DC failure. # cluster-replica-no-failover no # In order to setup your cluster make sure to read the documentation # available at http://redis.io web site. ########################## CLUSTER DOCKER/NAT support ######################## # In certain deployments, Redis Cluster nodes address discovery fails, because # addresses are NAT-ted or because ports are forwarded (the typical case is # Docker and other containers). # # In order to make Redis Cluster working in such environments, a static # configuration where each node knows its public address is needed. The # following two options are used for this scope, and are: # # * cluster-announce-ip # * cluster-announce-port # * cluster-announce-bus-port # # Each instruct the node about its address, client port, and cluster message # bus port. The information is then published in the header of the bus packets # so that other nodes will be able to correctly map the address of the node # publishing the information. # # If the above options are not used, the normal Redis Cluster auto-detection # will be used instead. # # Note that when remapped, the bus port may not be at the fixed offset of # clients port + 10000, so you can specify any port and bus-port depending # on how they get remapped. If the bus-port is not set, a fixed offset of # 10000 will be used as usually. # # Example: # # cluster-announce-ip 10.1.1.5 # cluster-announce-port 6379 # cluster-announce-bus-port 6380 ################################## SLOW LOG ################################### # The Redis Slow Log is a system to log queries that exceeded a specified # execution time. The execution time does not include the I/O operations # like talking with the client, sending the reply and so forth, # but just the time needed to actually execute the command (this is the only # stage of command execution where the thread is blocked and can not serve # other requests in the meantime). # # You can configure the slow log with two parameters: one tells Redis # what is the execution time, in microseconds, to exceed in order for the # command to get logged, and the other parameter is the length of the # slow log. When a new command is logged the oldest one is removed from the # queue of logged commands. # The following time is expressed in microseconds, so 1000000 is equivalent # to one second. Note that a negative number disables the slow log, while # a value of zero forces the logging of every command. slowlog-log-slower-than 10000 # There is no limit to this length. Just be aware that it will consume memory. # You can reclaim memory used by the slow log with SLOWLOG RESET. slowlog-max-len 128 ################################ LATENCY MONITOR ############################## # The Redis latency monitoring subsystem samples different operations # at runtime in order to collect data related to possible sources of # latency of a Redis instance. # # Via the LATENCY command this information is available to the user that can # print graphs and obtain reports. # # The system only logs operations that were performed in a time equal or # greater than the amount of milliseconds specified via the # latency-monitor-threshold configuration directive. When its value is set # to zero, the latency monitor is turned off. # # By default latency monitoring is disabled since it is mostly not needed # if you don't have latency issues, and collecting data has a performance # impact, that while very small, can be measured under big load. Latency # monitoring can easily be enabled at runtime using the command # "CONFIG SET latency-monitor-threshold <milliseconds>" if needed. latency-monitor-threshold 0 ############################# EVENT NOTIFICATION ############################## # Redis can notify Pub/Sub clients about events happening in the key space. # This feature is documented at http://redis.io/topics/notifications # # For instance if keyspace events notification is enabled, and a client # performs a DEL operation on key "foo" stored in the Database 0, two # messages will be published via Pub/Sub: # # PUBLISH __keyspace@0__:foo del # PUBLISH __keyevent@0__:del foo # # It is possible to select the events that Redis will notify among a set # of classes. Every class is identified by a single character: # # K Keyspace events, published with __keyspace@<db>__ prefix. # E Keyevent events, published with __keyevent@<db>__ prefix. # g Generic commands (non-type specific) like DEL, EXPIRE, RENAME, ... # $ String commands # l List commands # s Set commands # h Hash commands # z Sorted set commands # x Expired events (events generated every time a key expires) # e Evicted events (events generated when a key is evicted for maxmemory) # A Alias for g$lshzxe, so that the "AKE" string means all the events. # # The "notify-keyspace-events" takes as argument a string that is composed # of zero or multiple characters. The empty string means that notifications # are disabled. # # Example: to enable list and generic events, from the point of view of the # event name, use: # # notify-keyspace-events Elg # # Example 2: to get the stream of the expired keys subscribing to channel # name __keyevent@0__:expired use: # # notify-keyspace-events Ex # # By default all notifications are disabled because most users don't need # this feature and the feature has some overhead. Note that if you don't # specify at least one of K or E, no events will be delivered. notify-keyspace-events "" ############################### ADVANCED CONFIG ############################### # Hashes are encoded using a memory efficient data structure when they have a # small number of entries, and the biggest entry does not exceed a given # threshold. These thresholds can be configured using the following directives. hash-max-ziplist-entries 512 hash-max-ziplist-value 64 # Lists are also encoded in a special way to save a lot of space. # The number of entries allowed per internal list node can be specified # as a fixed maximum size or a maximum number of elements. # For a fixed maximum size, use -5 through -1, meaning: # -5: max size: 64 Kb <-- not recommended for normal workloads # -4: max size: 32 Kb <-- not recommended # -3: max size: 16 Kb <-- probably not recommended # -2: max size: 8 Kb <-- good # -1: max size: 4 Kb <-- good # Positive numbers mean store up to _exactly_ that number of elements # per list node. # The highest performing option is usually -2 (8 Kb size) or -1 (4 Kb size), # but if your use case is unique, adjust the settings as necessary. list-max-ziplist-size -2 # Lists may also be compressed. # Compress depth is the number of quicklist ziplist nodes from *each* side of # the list to *exclude* from compression. The head and tail of the list # are always uncompressed for fast push/pop operations. Settings are: # 0: disable all list compression # 1: depth 1 means "don't start compressing until after 1 node into the list, # going from either the head or tail" # So: [head]->node->node->...->node->[tail] # [head], [tail] will always be uncompressed; inner nodes will compress. # 2: [head]->[next]->node->node->...->node->[prev]->[tail] # 2 here means: don't compress head or head->next or tail->prev or tail, # but compress all nodes between them. # 3: [head]->[next]->[next]->node->node->...->node->[prev]->[prev]->[tail] # etc. list-compress-depth 0 # Sets have a special encoding in just one case: when a set is composed # of just strings that happen to be integers in radix 10 in the range # of 64 bit signed integers. # The following configuration setting sets the limit in the size of the # set in order to use this special memory saving encoding. set-max-intset-entries 512 # Similarly to hashes and lists, sorted sets are also specially encoded in # order to save a lot of space. This encoding is only used when the length and # elements of a sorted set are below the following limits: zset-max-ziplist-entries 128 zset-max-ziplist-value 64 # HyperLogLog sparse representation bytes limit. The limit includes the # 16 bytes header. When an HyperLogLog using the sparse representation crosses # this limit, it is converted into the dense representation. # # A value greater than 16000 is totally useless, since at that point the # dense representation is more memory efficient. # # The suggested value is ~ 3000 in order to have the benefits of # the space efficient encoding without slowing down too much PFADD, # which is O(N) with the sparse encoding. The value can be raised to # ~ 10000 when CPU is not a concern, but space is, and the data set is # composed of many HyperLogLogs with cardinality in the 0 - 15000 range. hll-sparse-max-bytes 3000 # Streams macro node max size / items. The stream data structure is a radix # tree of big nodes that encode multiple items inside. Using this configuration # it is possible to configure how big a single node can be in bytes, and the # maximum number of items it may contain before switching to a new node when # appending new stream entries. If any of the following settings are set to # zero, the limit is ignored, so for instance it is possible to set just a # max entires limit by setting max-bytes to 0 and max-entries to the desired # value. stream-node-max-bytes 4096 stream-node-max-entries 100 # Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in # order to help rehashing the main Redis hash table (the one mapping top-level # keys to values). The hash table implementation Redis uses (see dict.c) # performs a lazy rehashing: the more operation you run into a hash table # that is rehashing, the more rehashing "steps" are performed, so if the # server is idle the rehashing is never complete and some more memory is used # by the hash table. # # The default is to use this millisecond 10 times every second in order to # actively rehash the main dictionaries, freeing memory when possible. # # If unsure: # use "activerehashing no" if you have hard latency requirements and it is # not a good thing in your environment that Redis can reply from time to time # to queries with 2 milliseconds delay. # # use "activerehashing yes" if you don't have such hard requirements but # want to free memory asap when possible. activerehashing yes # The client output buffer limits can be used to force disconnection of clients # that are not reading data from the server fast enough for some reason (a # common reason is that a Pub/Sub client can't consume messages as fast as the # publisher can produce them). # # The limit can be set differently for the three different classes of clients: # # normal -> normal clients including MONITOR clients # replica -> replica clients # pubsub -> clients subscribed to at least one pubsub channel or pattern # # The syntax of every client-output-buffer-limit directive is the following: # # client-output-buffer-limit <class> <hard limit> <soft limit> <soft seconds> # # A client is immediately disconnected once the hard limit is reached, or if # the soft limit is reached and remains reached for the specified number of # seconds (continuously). # So for instance if the hard limit is 32 megabytes and the soft limit is # 16 megabytes / 10 seconds, the client will get disconnected immediately # if the size of the output buffers reach 32 megabytes, but will also get # disconnected if the client reaches 16 megabytes and continuously overcomes # the limit for 10 seconds. # # By default normal clients are not limited because they don't receive data # without asking (in a push way), but just after a request, so only # asynchronous clients may create a scenario where data is requested faster # than it can read. # # Instead there is a default limit for pubsub and replica clients, since # subscribers and replicas receive data in a push fashion. # # Both the hard or the soft limit can be disabled by setting them to zero. client-output-buffer-limit normal 0 0 0 client-output-buffer-limit replica 256mb 64mb 60 client-output-buffer-limit pubsub 32mb 8mb 60 # Client query buffers accumulate new commands. They are limited to a fixed # amount by default in order to avoid that a protocol desynchronization (for # instance due to a bug in the client) will lead to unbound memory usage in # the query buffer. However you can configure it here if you have very special # needs, such us huge multi/exec requests or alike. # # client-query-buffer-limit 1gb # In the Redis protocol, bulk requests, that are, elements representing single # strings, are normally limited ot 512 mb. However you can change this limit # here. # # proto-max-bulk-len 512mb # Redis calls an internal function to perform many background tasks, like # closing connections of clients in timeout, purging expired keys that are # never requested, and so forth. # # Not all tasks are performed with the same frequency, but Redis checks for # tasks to perform according to the specified "hz" value. # # By default "hz" is set to 10. Raising the value will use more CPU when # Redis is idle, but at the same time will make Redis more responsive when # there are many keys expiring at the same time, and timeouts may be # handled with more precision. # # The range is between 1 and 500, however a value over 100 is usually not # a good idea. Most users should use the default of 10 and raise this up to # 100 only in environments where very low latency is required. hz 10 # Normally it is useful to have an HZ value which is proportional to the # number of clients connected. This is useful in order, for instance, to # avoid too many clients are processed for each background task invocation # in order to avoid latency spikes. # # Since the default HZ value by default is conservatively set to 10, Redis # offers, and enables by default, the ability to use an adaptive HZ value # which will temporary raise when there are many connected clients. # # When dynamic HZ is enabled, the actual configured HZ will be used as # as a baseline, but multiples of the configured HZ value will be actually # used as needed once more clients are connected. In this way an idle # instance will use very little CPU time while a busy instance will be # more responsive. dynamic-hz yes # When a child rewrites the AOF file, if the following option is enabled # the file will be fsync-ed every 32 MB of data generated. This is useful # in order to commit the file to the disk more incrementally and avoid # big latency spikes. aof-rewrite-incremental-fsync yes # When redis saves RDB file, if the following option is enabled # the file will be fsync-ed every 32 MB of data generated. This is useful # in order to commit the file to the disk more incrementally and avoid # big latency spikes. rdb-save-incremental-fsync yes # Redis LFU eviction (see maxmemory setting) can be tuned. However it is a good # idea to start with the default settings and only change them after investigating # how to improve the performances and how the keys LFU change over time, which # is possible to inspect via the OBJECT FREQ command. # # There are two tunable parameters in the Redis LFU implementation: the # counter logarithm factor and the counter decay time. It is important to # understand what the two parameters mean before changing them. # # The LFU counter is just 8 bits per key, it's maximum value is 255, so Redis # uses a probabilistic increment with logarithmic behavior. Given the value # of the old counter, when a key is accessed, the counter is incremented in # this way: # # 1. A random number R between 0 and 1 is extracted. # 2. A probability P is calculated as 1/(old_value*lfu_log_factor+1). # 3. The counter is incremented only if R < P. # # The default lfu-log-factor is 10. This is a table of how the frequency # counter changes with a different number of accesses with different # logarithmic factors: # # +--------+------------+------------+------------+------------+------------+ # | factor | 100 hits | 1000 hits | 100K hits | 1M hits | 10M hits | # +--------+------------+------------+------------+------------+------------+ # | 0 | 104 | 255 | 255 | 255 | 255 | # +--------+------------+------------+------------+------------+------------+ # | 1 | 18 | 49 | 255 | 255 | 255 | # +--------+------------+------------+------------+------------+------------+ # | 10 | 10 | 18 | 142 | 255 | 255 | # +--------+------------+------------+------------+------------+------------+ # | 100 | 8 | 11 | 49 | 143 | 255 | # +--------+------------+------------+------------+------------+------------+ # # NOTE: The above table was obtained by running the following commands: # # redis-benchmark -n 1000000 incr foo # redis-cli object freq foo # # NOTE 2: The counter initial value is 5 in order to give new objects a chance # to accumulate hits. # # The counter decay time is the time, in minutes, that must elapse in order # for the key counter to be divided by two (or decremented if it has a value # less <= 10). # # The default value for the lfu-decay-time is 1. A Special value of 0 means to # decay the counter every time it happens to be scanned. # # lfu-log-factor 10 # lfu-decay-time 1 ########################### ACTIVE DEFRAGMENTATION ####################### # # WARNING THIS FEATURE IS EXPERIMENTAL. However it was stress tested # even in production and manually tested by multiple engineers for some # time. # # What is active defragmentation? # ------------------------------- # # Active (online) defragmentation allows a Redis server to compact the # spaces left between small allocations and deallocations of data in memory, # thus allowing to reclaim back memory. # # Fragmentation is a natural process that happens with every allocator (but # less so with Jemalloc, fortunately) and certain workloads. Normally a server # restart is needed in order to lower the fragmentation, or at least to flush # away all the data and create it again. However thanks to this feature # implemented by Oran Agra for Redis 4.0 this process can happen at runtime # in an "hot" way, while the server is running. # # Basically when the fragmentation is over a certain level (see the # configuration options below) Redis will start to create new copies of the # values in contiguous memory regions by exploiting certain specific Jemalloc # features (in order to understand if an allocation is causing fragmentation # and to allocate it in a better place), and at the same time, will release the # old copies of the data. This process, repeated incrementally for all the keys # will cause the fragmentation to drop back to normal values. # # Important things to understand: # # 1. This feature is disabled by default, and only works if you compiled Redis # to use the copy of Jemalloc we ship with the source code of Redis. # This is the default with Linux builds. # # 2. You never need to enable this feature if you don't have fragmentation # issues. # # 3. Once you experience fragmentation, you can enable this feature when # needed with the command "CONFIG SET activedefrag yes". # # The configuration parameters are able to fine tune the behavior of the # defragmentation process. If you are not sure about what they mean it is # a good idea to leave the defaults untouched. # Enabled active defragmentation # activedefrag yes # Minimum amount of fragmentation waste to start active defrag # active-defrag-ignore-bytes 100mb # Minimum percentage of fragmentation to start active defrag # active-defrag-threshold-lower 10 # Maximum percentage of fragmentation at which we use maximum effort # active-defrag-threshold-upper 100 # Minimal effort for defrag in CPU percentage # active-defrag-cycle-min 5 # Maximal effort for defrag in CPU percentage # active-defrag-cycle-max 75 # Maximum number of set/hash/zset/list fields that will be processed from # the main dictionary scan # active-defrag-max-scan-fields 1000