Java进程占用内存过高，排查解决方法

最近收到邮件报警，说内存使作率达到84%。如下图：

解决方法：

A:可能是代码原因导致的问题：

1、使用命令：top 查看当前进程的状态

2、从上图可以看到PID：916的java进程占用内存较大。定位线程问题（通过命令查看PID 为25894 进程的线程情况）,命令：# ps p 916 -L -o pcpu,pmem,pid,tid,time,tname,cmd

 

 由此可以看到这PID：916的进程产生了很多线程。接下来就可以通过jstack查看内存使用的堆栈。

3、查看内存使用的堆栈：在这里我们挑选了TID=934的线程进行分析，首先需要将934这个id转换为16进制。需输入如下命令，

 printf "%x\n" 9731

 

4、将PID为916的堆栈信息打印到jstack.log中，命令：jstack -l 916 > jstack.log

 

5、

 查看堆栈信息文件，命令：vim jstack.log

   在进行搜索TID为2603的相关信息。如图：

6、分析

   可以看到这个线程状态为：RUNNABLE。是正在运行状态的

    另外其它的大部分线程状态为：WAITING。通过查看文件分析 看到大量 Java Thread State。

   说明它在等待另一个条件的发生，来把自己唤醒，或者干脆它是调用了 sleep(N)。

   此时线程状态大致为以下几种：

   java.lang.Thread.State: WAITING (parking)：一直等那个条件发生；

   java.lang.Thread.State: TIMED_WAITING (parking或sleeping)：定时的，那个条件不到来，也将定时唤醒自己。

 

7.代码优化：将文件发送给开发。优化下线程

B:可能是其他原因导致的问题：

1、使用ps命令:ps -ef | grep java | grep -v grep

查看当前java进程列表

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

由上图所示，可以看到java进程是Tomcat的启动进程，开启多个Tomcat启动进程，并且是同一个端口。由此，可以判断，是因为关闭Tomcat服务时，java进程没有自动关闭，导致内存没有释放。

2、使用lsof命令:lsof | grep java |grep -v grep

查看当前进程的运行状态

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)

通过上图所示：正常运行的Tomcat状态应为PID:29458的java进程

3、杀掉其他的java的进程

kill -9 PID

4、然后查看主机监控，果然内存使用率下降，网站运行正常