# 聊聊 Java 自带的那些*逆天*工具 | Nicksxs's Blog
原谅我的标题党，其实这些工具的确很厉害，之前其实介绍过一点相关的，是从我一次问题排查的过程中用到的，但是最近又有碰到一次排查问题，发现其实用 idea 直接 dump thread 是不现实的，毕竟服务器环境的没法这么操作，那就得用 Java 的那些工具了 jstack & jps譬如 jstack，这个命令其实不能更简单了看看 help 信息用-l参数可以打出锁的额外信息，然后后面的 p

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# 聊聊 Java 自带的那些*逆天*工具

发表于 2020-08-02 分类于 Java ， Thread dump ， 问题排查 ， 工具 阅读次数： 阅读次数： Disqus：

原谅我的标题党，其实这些工具的确很厉害，之前其实介绍过一点相关的，是从我一次问题排查的过程中用到的，但是最近又有碰到一次排查问题，发现其实用 idea 直接 `dump thread` 是不现实的，毕竟服务器环境的没法这么操作，那就得用 Java 的那些工具了

### jstack & jps

譬如 `jstack`，这个命令其实不能更简单了
看看 help 信息
用`-l`参数可以打出锁的额外信息，然后后面的 pid 就是进程 id 咯，机智的小伙伴会问了（就你这个小白才问这么蠢的问题🤦‍♂️），怎么看 Java 应用的进程呢
那就是 `jps` 了，命令也很简单，一般直接用 `jps`命令就好了，不过也可以 help 看一下
稍微解释下，-q是只显示进程 id，-m是输出给main 方法的参数，比如我在配置中加给参数
然后用 `jps -m`查看
`-v`加上小 v 的话就是打印 jvm 参数
还是有点东西，然后就继续介绍 jstack 了，然后我们看看 jstack 出来是啥，为了加点内容我加了个死锁

    public static void main(String[] args) throws InterruptedException {
            SpringApplication.run(ThreadDumpDemoApplication.class, args);
            ReentrantLock lock1 = new ReentrantLock();
            ReentrantLock lock2 = new ReentrantLock();
            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();
            Thread.sleep(10000);
        }

然后看看出来时怎么样的

    2020-08-02 21:50:32
    Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.201-b09 mixed mode):

    "DestroyJavaVM" #147 prio=5 os_prio=31 tid=0x00007fc9dd807000 nid=0x2603 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE

       Locked ownable synchronizers:
            - None

    "mythread2" #140 prio=5 os_prio=31 tid=0x00007fc9dd877000 nid=0x9903 waiting on condition [0x0000700006fb9000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f5d4330> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
            at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
            at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
            at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
            at com.nicksxs.thread_dump_demo.ThreadDumpDemoApplication$2.run(ThreadDumpDemoApplication.java:34)

       Locked ownable synchronizers:
            - <0x000000076f5d4360> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)

    "mythread1" #139 prio=5 os_prio=31 tid=0x00007fc9de873800 nid=0x9a03 waiting on condition [0x0000700006eb6000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f5d4360> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
            at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
            at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
            at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
            at com.nicksxs.thread_dump_demo.ThreadDumpDemoApplication$1.run(ThreadDumpDemoApplication.java:22)

       Locked ownable synchronizers:
            - <0x000000076f5d4330> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)

    "http-nio-8080-Acceptor" #137 daemon prio=5 os_prio=31 tid=0x00007fc9de1ac000 nid=0x9b03 runnable [0x0000700006db3000]
       java.lang.Thread.State: RUNNABLE
            at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
            at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422)
            at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250)
            - locked <0x000000076f1e4820> (a java.lang.Object)
            at org.apache.tomcat.util.net.NioEndpoint.serverSocketAccept(NioEndpoint.java:469)
            at org.apache.tomcat.util.net.NioEndpoint.serverSocketAccept(NioEndpoint.java:71)
            at org.apache.tomcat.util.net.Acceptor.run(Acceptor.java:95)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-ClientPoller" #136 daemon prio=5 os_prio=31 tid=0x00007fc9dd876800 nid=0x6503 runnable [0x0000700006cb0000]
       java.lang.Thread.State: RUNNABLE
            at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
            at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:198)
            at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:117)
            at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
            - locked <0x000000076f2978c8> (a sun.nio.ch.Util$3)
            - locked <0x000000076f2978b8> (a java.util.Collections$UnmodifiableSet)
            - locked <0x000000076f297798> (a sun.nio.ch.KQueueSelectorImpl)
            at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
            at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:709)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-10" #135 daemon prio=5 os_prio=31 tid=0x00007fc9de1af000 nid=0x9d03 waiting on condition [0x0000700006bad000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-9" #134 daemon prio=5 os_prio=31 tid=0x00007fc9de1ab800 nid=0x6403 waiting on condition [0x0000700006aaa000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-8" #133 daemon prio=5 os_prio=31 tid=0x00007fc9de873000 nid=0x9f03 waiting on condition [0x00007000069a7000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-7" #132 daemon prio=5 os_prio=31 tid=0x00007fc9df0a1800 nid=0xa103 waiting on condition [0x00007000068a4000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-6" #131 daemon prio=5 os_prio=31 tid=0x00007fc9df242800 nid=0x6103 waiting on condition [0x00007000067a1000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-5" #130 daemon prio=5 os_prio=31 tid=0x00007fc9de872000 nid=0x5f03 waiting on condition [0x000070000669e000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-4" #129 daemon prio=5 os_prio=31 tid=0x00007fc9de1a6000 nid=0x5e03 waiting on condition [0x000070000659b000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-3" #128 daemon prio=5 os_prio=31 tid=0x00007fc9de871800 nid=0x5c03 waiting on condition [0x0000700006498000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-2" #127 daemon prio=5 os_prio=31 tid=0x00007fc9dead9000 nid=0x5b03 waiting on condition [0x0000700006395000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-exec-1" #126 daemon prio=5 os_prio=31 tid=0x00007fc9ddb00000 nid=0x5a03 waiting on condition [0x0000700006292000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f26aa00> (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:107)
            at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "http-nio-8080-BlockPoller" #125 daemon prio=5 os_prio=31 tid=0x00007fc9df242000 nid=0xa503 runnable [0x000070000618f000]
       java.lang.Thread.State: RUNNABLE
            at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
            at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:198)
            at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:117)
            at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
            - locked <0x000000076f1eea30> (a sun.nio.ch.Util$3)
            - locked <0x000000076f1ee198> (a java.util.Collections$UnmodifiableSet)
            - locked <0x000000076f1ee010> (a sun.nio.ch.KQueueSelectorImpl)
            at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
            at org.apache.tomcat.util.net.NioBlockingSelector$BlockPoller.run(NioBlockingSelector.java:313)

       Locked ownable synchronizers:
            - None

    "container-0" #124 prio=5 os_prio=31 tid=0x00007fc9df06a000 nid=0x5803 waiting on condition [0x000070000608c000]
       java.lang.Thread.State: TIMED_WAITING (sleeping)
            at java.lang.Thread.sleep(Native Method)
            at org.apache.catalina.core.StandardServer.await(StandardServer.java:570)
            at org.springframework.boot.web.embedded.tomcat.TomcatWebServer$1.run(TomcatWebServer.java:197)

       Locked ownable synchronizers:
            - None

    "Catalina-utility-2" #123 prio=1 os_prio=31 tid=0x00007fc9de886000 nid=0xa80f waiting on condition [0x0000700005f89000]
       java.lang.Thread.State: WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076c88ab58> (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.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
            at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "Catalina-utility-1" #122 prio=1 os_prio=31 tid=0x00007fc9de884000 nid=0x5667 waiting on condition [0x0000700005e86000]
       java.lang.Thread.State: TIMED_WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076c88ab58> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
            at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
            at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
            at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "RMI Scheduler(0)" #15 daemon prio=5 os_prio=31 tid=0x00007fc9de9ee000 nid=0x5503 waiting on condition [0x0000700005d83000]
       java.lang.Thread.State: TIMED_WAITING (parking)
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x00000006c0015410> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
            at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
            at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
            at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
            at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "Attach Listener" #13 daemon prio=9 os_prio=31 tid=0x00007fc9df149800 nid=0x3c07 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE

       Locked ownable synchronizers:
            - None

    "RMI TCP Accept-0" #11 daemon prio=5 os_prio=31 tid=0x00007fc9df100000 nid=0x4003 runnable [0x0000700005977000]
       java.lang.Thread.State: RUNNABLE
            at java.net.PlainSocketImpl.socketAccept(Native Method)
            at java.net.AbstractPlainSocketImpl.accept(AbstractPlainSocketImpl.java:409)
            at java.net.ServerSocket.implAccept(ServerSocket.java:545)
            at java.net.ServerSocket.accept(ServerSocket.java:513)
            at sun.management.jmxremote.LocalRMIServerSocketFactory$1.accept(LocalRMIServerSocketFactory.java:52)
            at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:405)
            at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:377)
            at java.lang.Thread.run(Thread.java:748)

       Locked ownable synchronizers:
            - None

    "Service Thread" #9 daemon prio=9 os_prio=31 tid=0x00007fc9df0ce800 nid=0x4103 runnable [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE

       Locked ownable synchronizers:
            - None

    "C1 CompilerThread2" #8 daemon prio=9 os_prio=31 tid=0x00007fc9df0ce000 nid=0x4203 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE

       Locked ownable synchronizers:
            - None

    "C2 CompilerThread1" #7 daemon prio=9 os_prio=31 tid=0x00007fc9de0a3800 nid=0x3503 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE

       Locked ownable synchronizers:
            - None

    "C2 CompilerThread0" #6 daemon prio=9 os_prio=31 tid=0x00007fc9de89b000 nid=0x3403 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE

       Locked ownable synchronizers:
            - None

    "Monitor Ctrl-Break" #5 daemon prio=5 os_prio=31 tid=0x00007fc9df0ca000 nid=0x3303 runnable [0x0000700005468000]
       java.lang.Thread.State: RUNNABLE
            at java.net.SocketInputStream.socketRead0(Native Method)
            at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
            at java.net.SocketInputStream.read(SocketInputStream.java:171)
            at java.net.SocketInputStream.read(SocketInputStream.java:141)
            at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
            at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
            at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
            - locked <0x00000006c001b760> (a java.io.InputStreamReader)
            at java.io.InputStreamReader.read(InputStreamReader.java:184)
            at java.io.BufferedReader.fill(BufferedReader.java:161)
            at java.io.BufferedReader.readLine(BufferedReader.java:324)
            - locked <0x00000006c001b760> (a java.io.InputStreamReader)
            at java.io.BufferedReader.readLine(BufferedReader.java:389)
            at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:64)

       Locked ownable synchronizers:
            - None

    "Signal Dispatcher" #4 daemon prio=9 os_prio=31 tid=0x00007fc9de824000 nid=0x4503 runnable [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE

       Locked ownable synchronizers:
            - None

    "Finalizer" #3 daemon prio=8 os_prio=31 tid=0x00007fc9dd811800 nid=0x4f03 in Object.wait() [0x0000700005262000]
       java.lang.Thread.State: WAITING (on object monitor)
            at java.lang.Object.wait(Native Method)
            - waiting on <0x00000006c0008348> (a java.lang.ref.ReferenceQueue$Lock)
            at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
            - locked <0x00000006c0008348> (a java.lang.ref.ReferenceQueue$Lock)
            at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
            at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)

       Locked ownable synchronizers:
            - None

    "Reference Handler" #2 daemon prio=10 os_prio=31 tid=0x00007fc9de02a000 nid=0x5003 in Object.wait() [0x000070000515f000]
       java.lang.Thread.State: WAITING (on object monitor)
            at java.lang.Object.wait(Native Method)
            - waiting on <0x00000006c001b940> (a java.lang.ref.Reference$Lock)
            at java.lang.Object.wait(Object.java:502)
            at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
            - locked <0x00000006c001b940> (a java.lang.ref.Reference$Lock)
            at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

       Locked ownable synchronizers:
            - None

    "VM Thread" os_prio=31 tid=0x00007fc9df00b800 nid=0x2c03 runnable

    "GC task thread#0 (ParallelGC)" os_prio=31 tid=0x00007fc9de805000 nid=0x1e07 runnable

    "GC task thread#1 (ParallelGC)" os_prio=31 tid=0x00007fc9de003800 nid=0x2a03 runnable

    "GC task thread#2 (ParallelGC)" os_prio=31 tid=0x00007fc9df002000 nid=0x5403 runnable

    "GC task thread#3 (ParallelGC)" os_prio=31 tid=0x00007fc9df002800 nid=0x5203 runnable

    "VM Periodic Task Thread" os_prio=31 tid=0x00007fc9df11a800 nid=0x3a03 waiting on condition

    JNI global references: 1087

    Found one Java-level deadlock:
    =============================
    "mythread2":
      waiting for ownable synchronizer 0x000000076f5d4330, (a java.util.concurrent.locks.ReentrantLock$NonfairSync),
      which is held by "mythread1"
    "mythread1":
      waiting for ownable synchronizer 0x000000076f5d4360, (a java.util.concurrent.locks.ReentrantLock$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  <0x000000076f5d4330> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
            at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
            at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
            at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
            at com.nicksxs.thread_dump_demo.ThreadDumpDemoApplication$2.run(ThreadDumpDemoApplication.java:34)
    "mythread1":
            at sun.misc.Unsafe.park(Native Method)
            - parking to wait for  <0x000000076f5d4360> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
            at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
            at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
            at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
            at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
            at com.nicksxs.thread_dump_demo.ThreadDumpDemoApplication$1.run(ThreadDumpDemoApplication.java:22)

    Found 1 deadlock.

前面的信息其实上次就看过了，后面就可以发现有个死锁了，
上面比较长，把主要的截出来，就是这边的，这点就很强大了。

### jmap

惯例还是看一下帮助信息
这个相对命令比较多，不过因为现在 dump 下来我们可能会用文件模式，然后将文件下载下来使用 mat 进行分析，所以可以使用
`jmap -dump:live,format=b,file=heap.bin <pid>`
命令照着上面看的就是打印活着的对象，然后以二进制格式，文件名叫 heap.bin 然后最后就是进程 id，打印出来以后可以用 mat 打开
这样就可以很清晰的看到应用里的各种信息，jmap 直接在命令中还可以看很多信息，比如使用`jmap -histo <pid>`打印对象的实例数和对象占用的内存
`jmap -finalizerinfo <pid>` 打印正在等候回收的对象

#### 小tips

对于一些应用内存已经占满了，jstack 和 jmap 可能会连不上的情况，可以使用`-F`参数强制打印线程或者 dump 文件，但是要注意这两者使用的用户必须与 java 进程启动用户一致，并且使用的 jdk 也要一致

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