Java线程问题分析定位
分析步骤:
1、使用top命令查看系统资源占用情况,发现Java进程占用大量CPU资源,PID为11572;
2、显示进程详细列表命令:ps -mp 11572 -o THREAD,tid,time
找到消耗资源多的TID,如TID:112052
3、将TID转换成16进制:printf "%x\n" 12052
4、打印堆栈信息:jstack 11572 |grep 2f14 -A 30
Thread dump信息如下:
"thread1" prio=6 tid=0x02de8400 nid=0x2688 runnable [0x0320f000] java.lang.Thread.State: RUNNABLE at DeadLock.callLongTime(DeadLock.java:63) at DeadLock$2.run(DeadLock.java:41) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722)
Locked ownable synchronizers: - <0x22be1488> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
"thread2" prio=6 tid=0x02de6c00 nid=0x218c waiting on condition [0x031bf000] java.lang.Thread.State: WAITING (parking) at sun.misc.Unsafe.park(Native Method) - parking to wait for <0x22be1488> (a java.util.concurrent.locks.ReentrantLock$NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:867) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1197) at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:214) at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:290) at DeadLock$2.run(DeadLock.java:40) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722)
Locked ownable synchronizers: - <0x22be64e0> (a java.util.concurrent.ThreadPoolExecutor$Worker)
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线程“thread2”处于WAITING状态,- parking to wait for <0x22be1488>,等待给0x22be1488的地址,而0x22be1488地址正被“thread1”上锁,Dump日志中有大量线程等待给这个地址上锁,就会出现线程等待资源超时。