jstack命令使用

jstack用法
/opt/java8/bin/jstack

Usage:
jstack [-l]
(to connect to running process) 连接活动线程
jstack -F [-m] [-l]
(to connect to a hung process) 连接阻塞线程
jstack [-m] [-l]
(to connect to a core file) 连接dump的文件
jstack [-m] [-l] [server_id@]
(to connect to a remote debug server) 连接远程服务器

Options:
-F to force a thread dump. Use when jstack does not respond (process is hung)
-m to print both java and native frames (mixed mode)
-l long listing. Prints additional information about locks
-h or -help to print this help message

jstack查看输出
/opt/java8/bin/jstack -l 28367

2019-06-25 15:04:46
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.77-b03 mixed mode):

"Attach Listener" #453 daemon prio=9 os_prio=0 tid=0x00007f9f94001000 nid=0xf30 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE

Locked ownable synchronizers:
- None

"grpc-default-executor-263" #452 daemon prio=5 os_prio=0 tid=0x00007f9f4c01f800 nid=0x9aa waiting on condition [0x00007f9f398bd000]
java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000007400243f0> (a java.util.concurrent.SynchronousQueue(TransferStack) at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215) at java.util.concurrent.SynchronousQueue)TransferStack.awaitFulfill(SynchronousQueue.java:460)
at java.util.concurrent.SynchronousQueue(TransferStack.transfer(SynchronousQueue.java:362) at java.util.concurrent.SynchronousQueue.poll(SynchronousQueue.java:941) at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1066) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127) at java.util.concurrent.ThreadPoolExecutor)Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)

Locked ownable synchronizers:
- None

"http-bio-8080-exec-10" #235 daemon prio=5 os_prio=0 tid=0x0000000001bcc800 nid=0x3c13 waiting on condition [0x00007f9f384a9000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x0000000743d26638> (a java.util.concurrent.locks.AbstractQueuedSynchronizer(ConditionObject) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer)ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
at java.util.concurrent.ThreadPoolExecutor(Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread)WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

Locked ownable synchronizers:
- None

jstack统计线程数
/opt/java8/bin/jstack -l 28367 | grep 'java.lang.Thread.State' | wc -l

jstack检测死锁
死锁代码
public class DeathLock {

private static Lock lock1 = new ReentrantLock();
private static Lock lock2 = new ReentrantLock();

public static void deathLock() {
    Thread t1 = new Thread() {
        @Override
        public void run() {
            try {
                lock1.lock();
                TimeUnit.SECONDS.sleep(1);
                lock2.lock();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };
    Thread t2 = new Thread() {
        @Override
        public void run() {
            try {
                lock2.lock();
                TimeUnit.SECONDS.sleep(1);
                lock1.lock();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };

    t1.setName("mythread1");
    t2.setName("mythread2");
    t1.start();
    t2.start();
}

public static void main(String[] args) {
    deathLock();
}

}
死锁日志
"mythread2" #12 prio=5 os_prio=0 tid=0x0000000058ef7800 nid=0x1ab4 waiting on condition [0x0000000059f8f000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000d602d610> (a java.util.concurrent.lock
s.ReentrantLock(NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInt errupt(AbstractQueuedSynchronizer.java:836) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(A bstractQueuedSynchronizer.java:870) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(Abstrac tQueuedSynchronizer.java:1199) at java.util.concurrent.locks.ReentrantLock)NonfairSync.lock(ReentrantLo
ck.java:209)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)

    at DeathLock$2.run(DeathLock.java:34)

Locked ownable synchronizers:
- <0x00000000d602d640> (a java.util.concurrent.locks.ReentrantLock$Nonfa
irSync)

"mythread1" #11 prio=5 os_prio=0 tid=0x0000000058ef7000 nid=0x3e68 waiting on condition [0x000000005947f000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000d602d640> (a java.util.concurrent.lock
s.ReentrantLock(NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInt errupt(AbstractQueuedSynchronizer.java:836) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(A bstractQueuedSynchronizer.java:870) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(Abstrac tQueuedSynchronizer.java:1199) at java.util.concurrent.locks.ReentrantLock)NonfairSync.lock(ReentrantLo
ck.java:209)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)

    at DeathLock$1.run(DeathLock.java:22)

Locked ownable synchronizers:
- <0x00000000d602d610> (a java.util.concurrent.locks.ReentrantLock$Nonfa
irSync)

Found one Java-level deadlock:

"mythread2":
waiting for ownable synchronizer 0x00000000d602d610, (a java.util.concurrent.l
ocks.ReentrantLock(NonfairSync), which is held by "mythread1" "mythread1": waiting for ownable synchronizer 0x00000000d602d640, (a java.util.concurrent.l ocks.ReentrantLock)NonfairSync),
which is held by "mythread2"

Java stack information for the threads listed above:

"mythread2":
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000d602d610> (a java.util.concurrent.lock
s.ReentrantLock(NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInt errupt(AbstractQueuedSynchronizer.java:836) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(A bstractQueuedSynchronizer.java:870) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(Abstrac tQueuedSynchronizer.java:1199) at java.util.concurrent.locks.ReentrantLock)NonfairSync.lock(ReentrantLo
ck.java:209)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)

    at DeathLock$2.run(DeathLock.java:34)

"mythread1":
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000d602d640> (a java.util.concurrent.lock
s.ReentrantLock(NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInt errupt(AbstractQueuedSynchronizer.java:836) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(A bstractQueuedSynchronizer.java:870) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(Abstrac tQueuedSynchronizer.java:1199) at java.util.concurrent.locks.ReentrantLock)NonfairSync.lock(ReentrantLo
ck.java:209)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)

    at DeathLock$1.run(DeathLock.java:22)

Found 1 deadlock.

jstack检测cpu高
步骤一：查看cpu占用高进程
top

Mem: 16333644k total, 9472968k used, 6860676k free, 165616k buffers
Swap: 0k total, 0k used, 0k free, 6665292k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
17850 root 20 0 7588m 112m 11m S 100.7 0.7 47:53.80 java
1552 root 20 0 121m 13m 8524 S 0.7 0.1 14:37.75 AliYunDun
3581 root 20 0 9750m 2.0g 13m S 0.7 12.9 298:30.20 java
1 root 20 0 19360 1612 1308 S 0.0 0.0 0:00.81 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root RT 0 0 0 0 S 0.0 0.0 0:00.14 migration/0

步骤二：查看cpu占用高线程
top -H -p 17850

top - 17:43:15 up 5 days, 7:31, 1 user, load average: 0.99, 0.97, 0.91
Tasks: 32 total, 1 running, 31 sleeping, 0 stopped, 0 zombie
Cpu(s): 3.7%us, 8.9%sy, 0.0%ni, 87.4%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 16333644k total, 9592504k used, 6741140k free, 165700k buffers
Swap: 0k total, 0k used, 0k free, 6781620k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
17880 root 20 0 7588m 112m 11m R 99.9 0.7 50:47.43 java
17856 root 20 0 7588m 112m 11m S 0.3 0.7 0:02.08 java
17850 root 20 0 7588m 112m 11m S 0.0 0.7 0:00.00 java
17851 root 20 0 7588m 112m 11m S 0.0 0.7 0:00.23 java
17852 root 20 0 7588m 112m 11m S 0.0 0.7 0:02.09 java
17853 root 20 0 7588m 112m 11m S 0.0 0.7 0:02.12 java
17854 root 20 0 7588m 112m 11m S 0.0 0.7 0:02.07 java

步骤三：转换线程ID
printf "%x " 17880
45d8

步骤四：定位cpu占用线程

jstack 17850|grep 45d8 -A 30
"pool-1-thread-11" #20 prio=5 os_prio=0 tid=0x00007fc860352800 nid=0x45d8 runnable [0x00007fc8417d2000]
java.lang.Thread.State: RUNNABLE
at java.io.FileOutputStream.writeBytes(Native Method)
at java.io.FileOutputStream.write(FileOutputStream.java:326)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
- locked <0x00000006c6c2e708> (a java.io.BufferedOutputStream)
at java.io.PrintStream.write(PrintStream.java:482)
- locked <0x00000006c6c10178> (a java.io.PrintStream)
at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
at sun.nio.cs.StreamEncoder.flushBuffer(StreamEncoder.java:104)
- locked <0x00000006c6c26620> (a java.io.OutputStreamWriter)
at java.io.OutputStreamWriter.flushBuffer(OutputStreamWriter.java:185)
at java.io.PrintStream.write(PrintStream.java:527)
- eliminated <0x00000006c6c10178> (a java.io.PrintStream)
at java.io.PrintStream.print(PrintStream.java:597)
at java.io.PrintStream.println(PrintStream.java:736)
- locked <0x00000006c6c10178> (a java.io.PrintStream)
at com.demo.guava.HardTask.call(HardTask.java:18)
at com.demo.guava.HardTask.call(HardTask.java:9)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)

"pool-1-thread-10" #19 prio=5 os_prio=0 tid=0x00007fc860345000 nid=0x45d7 waiting on condition [0x00007fc8418d3000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006c6c14178> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)

作者：晴天哥_374
链接：https://www.jianshu.com/p/8d5782bc596e
来源：简书
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