Java CPU性能分析工具代码实例

这篇文章主要介绍了java cpu性能分析工具代码实例,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

背景

有处理过生产问题的同学基本都能遇到系统忽然缓慢，cpu突然飙升，甚至整个应用请求不可用。当出现这种情况下，在不影响数据准确性的前提下，我们应该尽快导出jstack和内存信息，然后重启系统，尽快回复系统的可用性，避免用户体验过差。本文针对cpu飙升问题，提供该问题的排查思路，从而能够快速定位到某线程甚至某快代码导致cpu飙升，从而提供处理该问题的思路。

排查过程

• 通过top命令查看cpu飙升的java进程pid
• 通过ps -mp [pid] -o thread,tid,time查看该进程下所拥有的线程及各个线程占用cpu的使用率，并且记录cpu使用率过高的线程id号
• 将线程id号转换为16进程的数值记为tid_hex
• 使用jdk自带jstack监控命令
• 使用命令jstack [pid] | grep tid_hex -a100命令输出该线程的堆栈信息
• 根据堆栈信息分析代码。

通过以上步骤可以查找出导致cpu飙升的相关代码位置，然后对代码进行code review即可。

工具封装

以上步骤已经封装为脚本文件,通过以下脚本文件只需要指定进程id即pid即可导出默认前5条导致cpu率过高的堆栈信息。

已上传github :

./java-thread-top.sh -p pid

#!/bin/bash
# @function
# find out the highest cpu consumed threads of java processes, and print the stack of these threads.
# @github https://github.com/cjunn/script_tool/
# @author cjunn
# @date sun jan 12 2020 21:08:58 gmt+0800
#

pid='';
count=5;

function usage(){
  readonly prog="`basename $0`"
  cat <<eof
usage: ${prog} [option]
find out the highest cpu consumed threads of java processes,
and print the stack of these threads.
example:
 ${prog} -p <pid> -c 5   # show top 5 busy java threads info
output control:
 -p, --pid <java pid>   find out the highest cpu consumed threads from
              the specified java process.
              default from all java process.
 -c, --count <num>     set the thread count to show, default is 5.
miscellaneous:
 -h, --help        display this help and exit.
eof
}

#1.collect script parameters
#2.check whether pid exists
if [ $# -gt 0 ];
then
  while true; do
    case "$1" in
    -c|--count)
      count="$2"
      shift 2
      ;;
    -p|--pid)
      pid="$2"
      shift 2
      ;;
    -h|--help)
      usage
      exit 0;
      ;;
    --)
      shift
      break
      ;;
    *)
      shift
      if [ -z "$1" ] ; then
        break
      fi
      ;;
    esac
  done
fi
if [ ! -n "$pid" ] ;then
  echo "error: -p is empty"
  exit 1;
fi

function worker(){
  #1.query all threads according to pid.
  #2.delete header and first line information.
  #3.according to the second column of cpu to sort, reverse display.
  #4.delete the count + 1 to last column based on the count value.
  #5.get cpu utilization, tid value, thread used time, and assign them to cpu, tid, time respectively.
  #6.perform hex conversion on tid.
  #7.use jdk to monitor all threads of jstack output pid.
  #8.use awk to regularly query the thread information of tid_hex required.
  #9.display the stack information of count before thread busy.
  local whilec=0;
  ps -mp $pid -o thread,tid,time | sed '1,2d' | sort -k 2 -n -r |sed $[$count+1]',$d' | awk '{print $2,$8,$9}' | while read cpu tid time
  do
      tid_hex=$(printf "%x" $tid);
      echo "====================== tid:${tid} tid_hex:${tid_hex} cpu:${cpu} time:${time} ======================";
      jstack $pid | awk 'begin {rs = "\n\n+";ors = "\n\n"} /'${tid_hex}'/ {print $0}'
      echo "";
      whilec=$[$whilec+1];
  done
  if [ $whilec -eq 0 ] ; then
    echo "error : thread not found, make sure pid exists.";
  fi

}
worker

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。