常用命令
# 按照 CPU 使用率排序输出进程信息
ps -eo pid,ppid,%cpu,%mem,cmd --sort=-%cpu# 监控对应 pid 进程下的所有线程按照 CPU 排序
top -Hp "$pid" -o %CPU # jstack 输出 JVM 堆栈信息
jstack $pid
演示事例
查看高负载 Java 进程获取到对应 pid
$ ps -eo pid,ppid,%cpu,%mem,cmd --sort=-%cpuPID PPID %CPU %MEM CMD4432 4288 102 1.2 /usr/bin/qemu-x86_64 /usr/lib/jvm/java-1.8.0/bin/java java -cp mytomcat.jar co4288 0 0.2 0.2 /usr/bin/qemu-x86_64 /bin/bash /bin/bash1 0 0.0 0.1 /usr/bin/qemu-x86_64 /bin/sh /bin/sh /home/user/run.sh29 1 0.0 0.2 /usr/bin/qemu-x86_64 /usr/bin/sudo sudo /usr/sbin/sshd -D34 29 0.0 0.2 /usr/bin/qemu-x86_64 /usr/sbin/sshd /usr/sbin/sshd -D37 1 0.0 0.0 /usr/bin/qemu-x86_64 /usr/bin/tail tail -f /dev/null411 1 0.0 1.2 /usr/bin/qemu-x86_64 /usr/lib/jvm/java-1.8.0/bin/java java -cp mytomcat.jar co1892 0 0.0 0.2 /usr/bin/qemu-x86_64 /bin/bash /bin/bash3671 1 0.0 0.0 [java] <defunct>3759 1 0.0 0.0 [java] <defunct>3839 1 0.0 0.0 [jstack] <defunct>4017 1 0.0 0.0 [java] <defunct>4105 1 0.0 0.0 [java] <defunct>4466 1892 0.0 0.1 ps -eo pid,ppid,%cpu,%mem,cmd --sort=-%cpu
查看 pid 为 4432 进程的线程 CPU 占用情况
$ top -Hp 4432 -o %CPU -n 1top - 09:30:22 up 1 day, 4:05, 0 users, load average: 1.04, 1.62, 1.85
Threads: 16 total, 1 running, 15 sleeping, 0 stopped, 0 zombie
%Cpu(s): 25.8 us, 0.0 sy, 0.0 ni, 72.7 id, 0.0 wa, 0.0 hi, 1.5 si, 0.0 st
KiB Mem : 8039920 total, 5078924 free, 469100 used, 2491896 buff/cache
KiB Swap: 1048572 total, 1048572 free, 0 used. 6990084 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 4435 user 20 0 4585612 98712 17288 R 99.9 1.2 1:24.68 java 4432 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.05 java 4434 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4436 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4437 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4438 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4439 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4440 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4441 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4442 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4443 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4444 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.17 java 4445 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4446 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.18 java 4447 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.00 java 4448 user 20 0 4585612 98712 17288 S 0.0 1.2 0:00.06 java
可见该进程下 pid 为 4435 的线程 CPU 占用率最高将其换算为 16 进制 4435 = 0x1153
将 4432 堆栈信息导出并检索 4435 （jstack 导出的线程 id 是 16 进制）线程的调用情况
$ jstack 4432 > 4432.log
$ less 4432.log # /0x1153
定位到具体的线程调用情况
"main" #1 prio=5 os_prio=0 tid=0x0000004004009440 nid=0x1153 runnable [0x0000004002f36000]java.lang.Thread.State: RUNNABLEat com.ft.mytomcat.MyTomcat.main(MyTomcat.java:71)
定位到业务代码
利用 arthas
$ java -jar arthas-boot.jar
[INFO] JAVA_HOME: /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.171-8.b10.el7_5.x86_64/jre
[INFO] arthas-boot version: 3.7.1
[INFO] Found existing java process, please choose one and input the serial number of the process, eg : 1. Then hit ENTER.
* [1]: 4432 com.ft.mytomcat.MyTomcat
1
[INFO] arthas home: /tmp
[INFO] Try to attach process 4432
Picked up JAVA_TOOL_OPTIONS:
[INFO] Attach process 4432 success.
[INFO] arthas-client connect 127.0.0.1 3658,---. ,------. ,--------.,--. ,--. ,---. ,---. / O \ | .--. ''--. .--'| '--' | / O \ ' .-'
| .-. || '--'.' | | | .--. || .-. |`. `-.
| | | || |\ \ | | | | | || | | |.-' |
`--' `--'`--' '--' `--' `--' `--'`--' `--'`-----' wiki https://arthas.aliyun.com/doc
tutorials https://arthas.aliyun.com/doc/arthas-tutorials.html
version 3.7.1
main_class
pid 4432
time 2023-12-25 01:45:20 [arthas@4432]$ thread -n 1
"main" Id=1 cpuUsage=99.77% deltaTime=209ms time=11449914ms RUNNABLEat com.ft.mytomcat.MyTomcat.main(MyTomcat.java:71)[arthas@4432]$ stop
Resetting all enhanced classes ...
Affect(class count: 0 , method count: 0) cost in 7 ms, listenerId: 0
Arthas Server is going to shutdown...
[arthas@4432]$ session (bb9f4723-d996-4309-868d-cdea6fa62cb4) is closed because server is going to shutdown.
使用完 arthas 记得 stop
