Syntax: client_header_timeout time;
Default:
client_header_timeout 60s;
Context: http, server
Defines a timeout for reading client request header. If a client does not transmit the entire header within this time,
the 408 (Request Time-out) error is returned to the client.
Syntax: client_body_timeout time;
Default:
client_body_timeout 60s;
Context: http, server, location
Defines a timeout for reading client request body. The timeout is set only for a period between two successive read operations, not for the transmission of the whole request body.
If a client does not transmit anything within this time,
the 408 (Request Time-out) error is returned to the client.
從客戶端讀取request body時，兩次相鄰數據包讀取超時時間。
Syntax: keepalive_timeout timeout [header_timeout];
Default:
keepalive_timeout 75s;
Context: http, server, location
The first parameter sets a timeout during which a keep-alive client connection will stay open on the server side. The zero value disables keep-alive client connections.
The optional second parameter sets a value in the “Keep-Alive: timeout=time” response header field. Two parameters may differ.
Syntax: lingering_timeout time;
Default:
lingering_timeout 5s;
Context: http, server, location
When lingering_close is in effect, this directive specifies the maximum waiting time for more client data to arrive. If data are not received during this time,
the connection is closed. Otherwise, the data are read and ignored, and nginx starts waiting for more data again.
The “wait-read-ignore” cycle is repeated, but no longer than specified by the lingering_time directive.
Syntax: resolver_timeout time;
Default:
resolver_timeout 30s;
Context: http, server, location
Sets a timeout for name resolution, for example: resolver_timeout 5s;
域名解析的超時時間，默認30s
Syntax: send_timeout time;
Default:
send_timeout 60s;
Context: http, server, location
Sets a timeout for transmitting a response to the client. The timeout is set only between two successive write operations,
not for the transmission of the whole response. If the client does not receive anything within this time, the connection is closed.
客戶端從nginx相隔該時間為收到數據包，則連接關閉。
Syntax: proxy_connect_timeout time;
Default:
proxy_connect_timeout 60s;
Context: http, server, location
Defines a timeout for establishing a connection with a proxied server. It should be noted that this timeout cannot usually exceed 75 seconds.
nginx與upstream服務器用來建立連接的超時時間，默認60s，一般不應該超過75秒。
Syntax: proxy_read_timeout time;
Default:
proxy_read_timeout 60s;
Context: http, server, location
Defines a timeout for reading a response from the proxied server. The timeout is set only between two successive read operations,
not for the transmission of the whole response. If the proxied server does not transmit anything within this time, the connection is closed.
nginx從upstream讀取數據包的超時時間，往往一整個response分多個數據包返回，這個超時定義的是相鄰兩次數據包之間的間隔。
Syntax: proxy_send_timeout time;
Default:
proxy_send_timeout 60s;
Context: http, server, location
Sets a timeout for transmitting a request to the proxied server. The timeout is set only between two successive write operations,
not for the transmission of the whole request. If the proxied server does not receive anything within this time, the connection is closed.
與上面proxy_read_timeout對應，這個定義的是nginx向upstream寫數據，upstream服務器相鄰兩次的收取數據包的最大間隔時間。