最近收到郵件報警，說內存使作率達到84%。如下圖：
解決方法：
A:可能是代碼原因導致的問題：
1、使用命令：top 查看當前進程的狀態
2、從上圖可以看到PID：916的java進程占用內存較大。定位線程問題（通過命令查看PID 為25894 進程的線程情況）,命令：# ps p 916 -L -o pcpu,pmem,pid,tid,time,tname,cmd
由此可以看到這PID：916的進程產生了很多線程。接下來就可以通過jstack查看內存使用的堆棧。
3、查看內存使用的堆棧：在這里我們挑選了TID=934的線程進行分析，首先需要將934這個id轉換為16進制。需輸入如下命令，
printf "%x\n" 9731
4、將PID為916的堆棧信息打印到jstack.log中，命令：jstack -l 916 > jstack.log
5、
查看堆棧信息文件，命令：vim jstack.log
在進行搜索TID為2603的相關信息。如圖：
6、分析
可以看到這個線程狀態為：RUNNABLE。是正在運行狀態的
另外其它的大部分線程狀態為：WAITING。通過查看文件分析 看到大量 Java Thread State。
說明它在等待另一個條件的發生，來把自己喚醒，或者干脆它是調用了 sleep(N)。
此時線程狀態大致為以下幾種：
java.lang.Thread.State: WAITING (parking)：一直等那個條件發生；
java.lang.Thread.State: TIMED_WAITING (parking或sleeping)：定時的，那個條件不到來，也將定時喚醒自己。
7.代碼優化：將文件發送給開發。優化下線程
B:可能是其他原因導致的問題：
1、使用ps命令:ps -ef | grep java | grep -v grep
查看當前java進程列表
root 834 1 0 May13 ? 00:30:09 /usr/lib/jvm/java/bin/java -Djava.util.logging.config.file=/data/apache-tomcat-9.0.13/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /data/apache-tomcat-9.0.13/bin/bootstrap.jar:/data/apache-tomcat-9.0.13/bin/tomcat-juli.jar -Dcatalina.base=/data/apache-tomcat-9.0.13 -Dcatalina.home=/data/apache-tomcat-9.0.13 -Djava.io.tmpdir=/data/apache-tomcat-9.0.13/temp org.apache.catalina.startup.Bootstrap start root 1294 1 3 May13 ? 14:41:25 /usr/lib/jvm/java/bin/java -Djava.util.logging.config.file=/data/apache-tomcat-9.0.13/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /data/apache-tomcat-9.0.13/bin/bootstrap.jar:/data/apache-tomcat-9.0.13/bin/tomcat-juli.jar -Dcatalina.base=/data/apache-tomcat-9.0.13 -Dcatalina.home=/data/apache-tomcat-9.0.13 -Djava.io.tmpdir=/data/apache-tomcat-9.0.13/temp org.apache.catalina.startup.Bootstrap start root 2085 1 0 Mar05 ? 01:57:08 /usr/lib/jvm/java/bin/java -Djava.util.logging.config.file=/data/apache-tomcat-9.0.13/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /data/apache-tomcat-9.0.13/bin/bootstrap.jar:/data/apache-tomcat-9.0.13/bin/tomcat-juli.jar -Dcatalina.base=/data/apache-tomcat-9.0.13 -Dcatalina.home=/data/apache-tomcat-9.0.13 -Djava.io.tmpdir=/data/apache-tomcat-9.0.13/temp org.apache.catalina.startup.Bootstrap start root 12808 1 0 Mar08 ? 01:16:03 /usr/lib/jvm/java/bin/java -Djava.util.logging.config.file=/data/apache-tomcat-9.0.13/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /data/apache-tomcat-9.0.13/bin/bootstrap.jar:/data/apache-tomcat-9.0.13/bin/tomcat-juli.jar -Dcatalina.base=/data/apache-tomcat-9.0.13 -Dcatalina.home=/data/apache-tomcat-9.0.13 -Djava.io.tmpdir=/data/apache-tomcat-9.0.13/temp org.apache.catalina.startup.Bootstrap start root 19392 1 0 May09 ? 00:36:19 /usr/lib/jvm/java/bin/java -Djava.util.logging.config.file=/data/apache-tomcat-9.0.13/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /data/apache-tomcat-9.0.13/bin/bootstrap.jar:/data/apache-tomcat-9.0.13/bin/tomcat-juli.jar -Dcatalina.base=/data/apache-tomcat-9.0.13 -Dcatalina.home=/data/apache-tomcat-9.0.13 -Djava.io.tmpdir=/data/apache-tomcat-9.0.13/temp org.apache.catalina.startup.Bootstrap start root 19838 1 1 May09 ? 05:32:17 /usr/lib/jvm/java/bin/java -Djava.util.logging.config.file=/data/apache-tomcat-9.0.13/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /data/apache-tomcat-9.0.13/bin/bootstrap.jar:/data/apache-tomcat-9.0.13/bin/tomcat-juli.jar -Dcatalina.base=/data/apache-tomcat-9.0.13 -Dcatalina.home=/data/apache-tomcat-9.0.13 -Djava.io.tmpdir=/data/apache-tomcat-9.0.13/temp org.apache.catalina.startup.Bootstrap start root 21543 1 0 May27 ? 00:22:03 /usr/lib/jvm/java/bin/java -Djava.util.logging.config.file=/data/apache-tomcat-9.0.13/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /data/apache-tomcat-9.0.13/bin/bootstrap.jar:/data/apache-tomcat-9.0.13/bin/tomcat-juli.jar -Dcatalina.base=/data/apache-tomcat-9.0.13 -Dcatalina.home=/data/apache-tomcat-9.0.13 -Djava.io.tmpdir=/data/apache-tomcat-9.0.13/temp org.apache.catalina.startup.Bootstrap start root 22750 1 5 May27 ? 02:28:41 /usr/lib/jvm/java/bin/java -Djava.util.logging.config.file=/data/apache-tomcat-9.0.13/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /data/apache-tomcat-9.0.13/bin/bootstrap.jar:/data/apache-tomcat-9.0.13/bin/tomcat-juli.jar -Dcatalina.base=/data/apache-tomcat-9.0.13 -Dcatalina.home=/data/apache-tomcat-9.0.13 -Djava.io.tmpdir=/data/apache-tomcat-9.0.13/temp org.apache.catalina.startup.Bootstrap start
由上圖所示，可以看到java進程是Tomcat的啟動進程，開啟多個Tomcat啟動進程，並且是同一個端口。由此，可以判斷，是因為關閉Tomcat服務時，java進程沒有自動關閉，導致內存沒有釋放。
2、使用lsof命令:lsof | grep java |grep -v grep
查看當前進程的運行狀態
java 834 root cwd DIR 252,1 4096 393217 /root java 834 root rtd DIR 252,1 4096 2 / java 834 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 834 root mem REG 252,1 262896 269147 /usr/lib64/libjpeg.so.62.0.0 java 834 root mem REG 252,1 41400 792676 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libjavajpeg.so java 834 root mem REG 252,1 644072 266782 /usr/lib64/libfreetype.so.6.3.22 java 834 root mem REG 252,1 349032 792667 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libfontmanager.so java 834 root mem REG 252,1 29072 792665 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt_headless.so java 834 root mem REG 252,1 715224 792664 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt.so java 834 root mem REG 252,1 99174448 269459 /usr/lib/locale/locale-archive java 834 root mem REG 252,1 111440 656920 /lib64/libresolv-2.12.so java 834 root mem REG 252,1 27896 655389 /lib64/libnss_dns-2.12.so .................... java 1294 root cwd DIR 252,1 4096 393217 /root java 1294 root rtd DIR 252,1 4096 2 / java 1294 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 1294 root mem REG 252,1 99174448 269459 /usr/lib/locale/locale-archive java 1294 root mem REG 252,1 262896 269147 /usr/lib64/libjpeg.so.62.0.0 java 1294 root mem REG 252,1 41400 792676 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libjavajpeg.so java 1294 root mem REG 252,1 644072 266782 /usr/lib64/libfreetype.so.6.3.22 java 1294 root mem REG 252,1 349032 792667 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libfontmanager.so java 1294 root mem REG 252,1 29072 792665 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt_headless.so java 1294 root mem REG 252,1 715224 792664 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt.so java 1294 root mem REG 252,1 111440 656920 /lib64/libresolv-2.12.so java 1294 root mem REG 252,1 27896 655389 /lib64/libnss_dns-2.12.so java 1294 root mem REG 252,1 11920 131997 /var/cache/fontconfig/beeeeb3dfe132a8a0633a017c99ce0c0-le64.cache-3 java 1294 root mem REG 252,1 3203275 792699 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/charsets.jar java 1294 root mem REG 252,1 3509512 792747 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/resources.jar java 1294 root mem REG 252,1 477712 655369 /lib64/libfreeblpriv3.so java 1294 root mem REG 252,1 248720 655363 /lib64/libnspr4.so java 1294 root mem REG 252,1 18720 655370 /lib64/libplc4.so java 1294 root mem REG 252,1 14528 655377 /lib64/libplds4.so java 1294 root mem REG 252,1 191928 266783 /usr/lib64/libnssutil3.so java 1294 root mem REG 252,1 1337168 268947 /usr/lib64/libnss3.so ............ java 2085 root cwd DIR 252,17 4096 2621998 /data/apache-tomcat-9.0.13/bin java 2085 root rtd DIR 252,1 4096 2 / java 2085 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 2085 root mem REG 252,1 99174448 269459 /usr/lib/locale/locale-archive java 2085 root mem REG 252,1 111440 656920 /lib64/libresolv-2.12.so java 2085 root mem REG 252,1 27896 655389 /lib64/libnss_dns-2.12.so java 2085 root mem REG 252,1 3203275 792699 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/charsets.jar java 2085 root mem REG 252,1 3509512 792747 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/resources.jar java 2085 root mem REG 252,1 477712 655369 /lib64/libfreeblpriv3.so java 2085 root mem REG 252,1 248720 655363 /lib64/libnspr4.so java 2085 root mem REG 252,1 18720 655370 /lib64/libplc4.so java 2085 root mem REG 252,1 14528 655377 /lib64/libplds4.so java 2085 root mem REG 252,1 191928 266783 /usr/lib64/libnssutil3.so java 2085 root mem REG 252,1 1337168 268947 /usr/lib64/libnss3.so java 2085 root mem REG 252,1 185368 266802 /usr/lib64/libsmime3.so java 2085 root mem REG 252,1 336472 269139 /usr/lib64/libssl3.so java 2085 root mem REG 252,1 45720 792689 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libsunec.so java 2085 root mem REG 252,1 36088 792682 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libmanagement.so java 2085 root mem REG 252,1 98280 792684 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libnet.so java 2085 root mem REG 252,1 73416 792685 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libnio.so java 2085 root mem REG 252,17 34918 2622001 /data/apache-tomcat-9.0.13/bin/bootstrap.jar java 2085 root mem REG 252,1 73280094 792748 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/rt.jar java 2085 root mem REG 252,1 298029 792717 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/ext/sunjce_provider.jar ............ java 12808 root cwd DIR 252,1 4096 393217 /root java 12808 root rtd DIR 252,1 4096 2 / java 12808 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 12808 root mem REG 252,1 99174448 269459 /usr/lib/locale/locale-archive java 12808 root mem REG 252,1 111440 656920 /lib64/libresolv-2.12.so java 12808 root mem REG 252,1 27896 655389 /lib64/libnss_dns-2.12.so java 12808 root mem REG 252,1 3509512 792747 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/resources.jar java 12808 root mem REG 252,1 477712 655369 /lib64/libfreeblpriv3.so java 12808 root mem REG 252,1 248720 655363 /lib64/libnspr4.so java 12808 root mem REG 252,1 18720 655370 /lib64/libplc4.so java 12808 root mem REG 252,1 3203275 792699 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/charsets.jar java 12808 root mem REG 252,1 14528 655377 /lib64/libplds4.so java 12808 root mem REG 252,1 191928 266783 /usr/lib64/libnssutil3.so java 12808 root mem REG 252,1 1337168 268947 /usr/lib64/libnss3.so java 12808 root mem REG 252,1 185368 266802 /usr/lib64/libsmime3.so java 12808 root mem REG 252,1 336472 269139 /usr/lib64/libssl3.so java 12808 root mem REG 252,1 45720 792689 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libsunec.so java 12808 root mem REG 252,1 36088 792682 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libmanagement.so java 12808 root mem REG 252,1 98280 792684 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libnet.so java 12808 root mem REG 252,1 73416 792685 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libnio.so .......... java 19392 root cwd DIR 252,1 4096 393217 /root java 19392 root rtd DIR 252,1 4096 2 / java 19392 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 19392 root mem REG 252,1 262896 269147 /usr/lib64/libjpeg.so.62.0.0 java 19392 root mem REG 252,1 41400 792676 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libjavajpeg.so java 19392 root mem REG 252,1 644072 266782 /usr/lib64/libfreetype.so.6.3.22 java 19392 root mem REG 252,1 349032 792667 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libfontmanager.so java 19392 root mem REG 252,1 29072 792665 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt_headless.so java 19392 root mem REG 252,1 715224 792664 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt.so java 19392 root mem REG 252,1 99174448 269459 /usr/lib/locale/locale-archive java 19392 root mem REG 252,1 111440 656920 /lib64/libresolv-2.12.so java 19392 root mem REG 252,1 27896 655389 /lib64/libnss_dns-2.12.so java 19392 root mem REG 252,1 11920 131997 /var/cache/fontconfig/beeeeb3dfe132a8a0633a017c99ce0c0-le64.cache-3 java 19392 root mem REG 252,1 3203275 792699 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/charsets.jar java 19392 root mem REG 252,1 3509512 792747 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/resources.jar java 19392 root mem REG 252,1 477712 655369 /lib64/libfreeblpriv3.so java 19392 root mem REG 252,1 248720 655363 /lib64/libnspr4.so java 19392 root mem REG 252,1 18720 655370 /lib64/libplc4.so java 19392 root mem REG 252,1 14528 655377 /lib64/libplds4.so java 19392 root mem REG 252,1 191928 266783 /usr/lib64/libnssutil3.so ........... java 19838 root cwd DIR 252,1 4096 393217 /root java 19838 root rtd DIR 252,1 4096 2 / java 19838 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 19838 root mem REG 252,1 99174448 269459 /usr/lib/locale/locale-archive java 19838 root mem REG 252,1 262896 269147 /usr/lib64/libjpeg.so.62.0.0 java 19838 root mem REG 252,1 41400 792676 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libjavajpeg.so java 19838 root mem REG 252,1 644072 266782 /usr/lib64/libfreetype.so.6.3.22 java 19838 root mem REG 252,1 349032 792667 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libfontmanager.so java 19838 root mem REG 252,1 29072 792665 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt_headless.so java 19838 root mem REG 252,1 715224 792664 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt.so java 19838 root mem REG 252,1 11920 131997 /var/cache/fontconfig/beeeeb3dfe132a8a0633a017c99ce0c0-le64.cache-3 java 19838 root mem REG 252,1 111440 656920 /lib64/libresolv-2.12.so java 19838 root mem REG 252,1 27896 655389 /lib64/libnss_dns-2.12.so java 19838 root mem REG 252,1 3203275 792699 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/charsets.jar java 19838 root mem REG 252,1 3509512 792747 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/resources.jar java 19838 root mem REG 252,1 477712 655369 /lib64/libfreeblpriv3.so java 19838 root mem REG 252,1 248720 655363 /lib64/libnspr4.so java 19838 root mem REG 252,1 18720 655370 /lib64/libplc4.so java 19838 root mem REG 252,1 14528 655377 /lib64/libplds4.so ......... java 21543 root cwd DIR 252,1 4096 393217 /root java 21543 root rtd DIR 252,1 4096 2 / java 21543 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 21543 root mem REG 252,1 262896 269147 /usr/lib64/libjpeg.so.62.0.0 java 21543 root mem REG 252,1 41400 792676 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libjavajpeg.so java 21543 root mem REG 252,1 644072 266782 /usr/lib64/libfreetype.so.6.3.22 java 21543 root mem REG 252,1 349032 792667 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libfontmanager.so java 21543 root mem REG 252,1 29072 792665 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt_headless.so java 21543 root mem REG 252,1 715224 792664 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt.so java 21543 root mem REG 252,1 111440 656920 /lib64/libresolv-2.12.so java 21543 root mem REG 252,1 27896 655389 /lib64/libnss_dns-2.12.so java 21543 root mem REG 252,1 3509512 792747 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/resources.jar java 21543 root mem REG 252,1 3203275 792699 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/charsets.jar java 21543 root mem REG 252,1 11920 131997 /var/cache/fontconfig/beeeeb3dfe132a8a0633a017c99ce0c0-le64.cache-3 java 21543 root mem REG 252,1 477712 655369 /lib64/libfreeblpriv3.so java 21543 root mem REG 252,1 248720 655363 /lib64/libnspr4.so java 21543 root mem REG 252,1 18720 655370 /lib64/libplc4.so java 21543 root mem REG 252,1 14528 655377 /lib64/libplds4.so java 21543 root mem REG 252,1 191928 266783 /usr/lib64/libnssutil3.so ........ java 22750 root cwd DIR 252,1 4096 393217 /root java 22750 root rtd DIR 252,1 4096 2 / java 22750 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 22750 root mem REG 252,1 262896 269147 /usr/lib64/libjpeg.so.62.0.0 java 22750 root mem REG 252,1 41400 792676 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libjavajpeg.so java 22750 root mem REG 252,1 644072 266782 /usr/lib64/libfreetype.so.6.3.22 java 22750 root mem REG 252,1 349032 792667 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libfontmanager.so java 22750 root mem REG 252,1 29072 792665 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt_headless.so java 22750 root mem REG 252,1 715224 792664 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt.so java 22750 root mem REG 252,1 111440 656920 /lib64/libresolv-2.12.so java 22750 root mem REG 252,1 27896 655389 /lib64/libnss_dns-2.12.so java 22750 root mem REG 252,1 11920 131997 /var/cache/fontconfig/beeeeb3dfe132a8a0633a017c99ce0c0-le64.cache-3 java 22750 root mem REG 252,1 3203275 792699 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/charsets.jar java 22750 root mem REG 252,1 3509512 792747 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/resources.jar java 22750 root mem REG 252,1 477712 655369 /lib64/libfreeblpriv3.so java 22750 root mem REG 252,1 248720 655363 /lib64/libnspr4.so ........ java 29458 root cwd DIR 252,1 4096 393217 /root java 29458 root rtd DIR 252,1 4096 2 / java 29458 root txt REG 252,1 5128 917742 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/bin/java java 29458 root mem REG 252,1 99174448 269459 /usr/lib/locale/locale-archive java 29458 root mem REG 252,1 262896 269147 /usr/lib64/libjpeg.so.62.0.0 java 29458 root mem REG 252,1 41400 792676 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libjavajpeg.so java 29458 root mem REG 252,1 644072 266782 /usr/lib64/libfreetype.so.6.3.22 java 29458 root mem REG 252,1 349032 792667 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libfontmanager.so java 29458 root mem REG 252,1 29072 792665 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt_headless.so java 29458 root mem REG 252,1 715224 792664 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/lib/amd64/libawt.so java 29458 root mem REG 252,1 11920 131997 /var/cache/fontconfig/beeeeb3dfe132a8a0633a017c99ce0c0-le64.cache-3 ............ java 29458 root 235u IPv4 34489969 0t0 TCP localhost:57037->localhost:mysql (ESTABLISHED) java 29458 root 236u IPv4 34489971 0t0 TCP localhost:57036->localhost:mysql (ESTABLISHED) java 29458 root 237u IPv4 34489970 0t0 TCP localhost:57040->localhost:mysql (ESTABLISHED) java 29458 root 238u IPv4 34489982 0t0 TCP localhost:57042->localhost:mysql (ESTABLISHED) java 29458 root 239u IPv4 34489983 0t0 TCP localhost:57043->localhost:mysql (ESTABLISHED) java 29458 root 240u IPv4 34489984 0t0 TCP localhost:57046->localhost:mysql (ESTABLISHED)
通過上圖所示：正常運行的Tomcat狀態應為PID:29458的java進程
3、殺掉其他的java的進程
kill -9 PID
4、然后查看主機監控，果然內存使用率下降，網站運行正常
