1.Java程序
import java.io.Serializable;public class Test { public static void main(String[] args) throws InterruptedException { while (true){ //始终循环创立User对象 User user = new User(); user.userName1 = "username1"; user.userName2 = "userName2"; user.userName3 = "userName3"; user.userName4 = "userName4"; user.userName5 = "userName5"; user.userName6 = "userName6"; user.userName7 = "userName7"; user.userName8 = "userName8"; } } public static void service(){ return; } public static class User implements Serializable { public String userName1; public String userName2; public String userName3; public String userName4; public String userName5; public String userName6; public String userName7; public String userName8; public String userName9; public String userName10; public String userName11; public String userName12; public String userName13; public String userName14; public String userName15; public String userName16; }}2.top命令查看cpu占用率
top - 09:56:17 up 1 day, 9:53, 7 users, load average: 1.34, 0.95, 0.77Tasks: 139 total, 2 running, 137 sleeping, 0 stopped, 0 zombie%Cpu(s): 51.9 us, 3.8 sy, 0.0 ni, 43.6 id, 0.0 wa, 0.0 hi, 0.7 si, 0.0 stKiB Mem : 3880320 total, 137000 free, 3496672 used, 246648 buff/cacheKiB Swap: 2097148 total, 2076660 free, 20488 used. 159388 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 17679 root 20 0 3665040 32140 15900 S 91.0 0.8 0:18.84 java 15862 root 20 0 155032 5624 3936 S 0.7 0.1 0:30.12 sshd 24986 root 20 0 4607680 998.2m 12640 S 0.7 26.3 18:24.92 java 23783 root 20 0 151708 6408 1112 S 0.3 0.2 6:36.31 redis-sentinel 23790 root 20 0 149448 4840 1108 R 0.3 0.1 6:39.38 redis-sentinel 25350 root 20 0 4567896 973220 11788 S 0.3 25.1 12:45.53 java 25716 root 20 0 4574928 994456 11788 S 0.3 25.6 12:47.27 java 28449 root 20 0 155160 5644 3936 S 0.3 0.1 0:22.72 sshd 28610 root 20 0 162832 3032 1572 S 0.3 0.1 0:11.98 top 30011 root 20 0 155148 5628 3936 S 0.3 0.1 0:13.78 sshd 30158 root 20 0 162832 3024 1556 S 0.3 0.1 0:06.20 top 1 root 20 0 128104 4568 2736 S 0.0 0.1 0:04.42 systemd 2 root 20 0 0 0 0 S 0.0 0.0 0:00.04 kthreadd 4 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H 6 root 20 0 0 0 0 S 0.0 0.0 0:09.35 ksoftirqd/03.查看过程对应的线程占用cpu
top -p 23191 -H
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 23192 root 20 0 3665040 30560 15772 R 91.3 0.8 2:06.06 java 23191 root 20 0 3665040 30560 15772 S 0.0 0.8 0:00.00 java 23193 root 20 0 3665040 30560 15772 S 0.0 0.8 0:00.01 GC Thread#0 23194 root 20 0 3665040 30560 15772 S 0.0 0.8 0:00.00 G1 Main Marker 23195 root 20 0 3665040 30560 15772 S 0.0 0.8 0:00.00 G1 Conc#0 23196 root 20 0 3665040 30560 15772 S 0.0 0.8 0:00.00 G1 Refine#0 23197 root 20 0 3665040 30560 15772 S 0.0 0.8 0:00.01 G1 Young RemSet4.获取23191线程堆栈信息
jstack 23191 > 23191.log,找到对应的高cpu占用线程23192(0x5d54)线程的状态。能够通过堆栈信息看到是Test.java中的问题
"main" #1 prio=5 os_prio=0 cpu=265491.21ms elapsed=290.57s tid=0x00007f5830014800 nid=0x5d54 runnable [0x00007f58384a3000]java.lang.Thread.State: RUNNABLE at Test.main(Test.java:15)5.上述能够通过top + jstack进行查找高cpu线程和其堆栈信息
也能够通过脚本来实现查问高cpu占用线程
wget --no-check-certificate https://github.com/oldratlee/useful-scripts/archive/release-2.x.zipunzip release-2.x.zipgithub上的开源脚本间接执行/data/java/useful-scripts-release-2.x/bin中的show-busy-java-threads脚本即可查看，默认显示前5名线程后果
[1] Busy(90.4%) thread(14366/0x381e) stack of java process(14365) under user(root):"main" #1 prio=5 os_prio=0 cpu=16787.88ms elapsed=18.53s tid=0x00007f4964014800 nid=0x381e runnable [0x00007f496dc9f000] java.lang.Thread.State: RUNNABLE at Test.main(Test.java:15)[2] Busy(0.0%) thread(14365/0x381d) stack of java process(14365) under user(root):[3] Busy(0.0%) thread(24040/0x5de8) stack of java process(24040) under user(root):[4] Busy(0.0%) thread(24043/0x5deb) stack of java process(24040) under user(root):"main" #1 prio=5 os_prio=0 cpu=787.79ms elapsed=121813.53s tid=0x00007f9e9c015000 nid=0x5deb in Object.wait() [0x00007f9ea6296000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(java.base@11.0.7/Native Method) - waiting on <0x00000000c631f8a0> (a org.apache.zookeeper.server.quorum.QuorumPeer) at java.lang.Thread.join(java.base@11.0.7/Thread.java:1305) - waiting to re-lock in wait() <0x00000000c631f8a0> (a org.apache.zookeeper.server.quorum.QuorumPeer) at java.lang.Thread.join(java.base@11.0.7/Thread.java:1379) at org.apache.zookeeper.server.quorum.QuorumPeerMain.runFromConfig(QuorumPeerMain.java:171) at org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:114) at org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:81)[5] Busy(0.0%) thread(24098/0x5e22) stack of java process(24098) under user(root):