【发布时间】：2019-10-08 21:05:23
【问题描述】：
我们有一个在大型应用程序的构建过程中使用的 Java 命令行实用程序。从最近（显然是在将 Java 升级到 OpenJDK 运行时环境（build 1.8.0_212-b04）之后——该程序不经常使用，所以我没有注意到这到底是什么时候开始发生的）它在@987654321 之后挂起大约一分钟@ 已完成。 IE。它挂在 Java 内部的某个地方，不在我们的代码中，尽管我们的代码可能会以某种方式间接导致这种情况。
该程序使用 Javassist (3.25) 来检测一些以前使用 javac 编译的 Java 类。不幸的是，我无法发布程序本身，因为它非常庞大、复杂并且是专有的。
挂起大约一分钟后，程序正常退出——进程返回码为零，没有任何内容被打印到 stderr 或 stdout。产生的结果也符合预期。
下面是使用jstack 实用程序从“挂起”进程中提取的线程堆栈转储。如您所见，我们的程序中不再有线程执行任何操作，此时所有线程都在 Java 内部。
有没有人遇到过类似的事情或有什么想法？
2019-05-22 12:51:34
Full thread dump OpenJDK 64-Bit Server VM (25.212-b04 mixed mode):
"Attach Listener" #12 daemon prio=9 os_prio=0 tid=0x00007f196c001000 nid=0x3c3a waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"DestroyJavaVM" #11 prio=5 os_prio=0 tid=0x00007f19c0059800 nid=0x3b6c waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"pool-1-thread-1" #10 prio=5 os_prio=0 tid=0x00007f19c0d1b800 nid=0x3b8e waiting on condition [0x00007f1985f21000]
java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x0000000776280730> (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$TransferStack.transfer(SynchronousQueue.java:362)
at java.util.concurrent.SynchronousQueue.poll(SynchronousQueue.java:941)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1073)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"Service Thread" #9 daemon prio=9 os_prio=0 tid=0x00007f19c0145800 nid=0x3b87 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C1 CompilerThread3" #8 daemon prio=9 os_prio=0 tid=0x00007f19c013a000 nid=0x3b86 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread2" #7 daemon prio=9 os_prio=0 tid=0x00007f19c0138000 nid=0x3b85 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007f19c0136000 nid=0x3b84 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 tid=0x00007f19c0133000 nid=0x3b83 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Signal Dispatcher" #4 daemon prio=9 os_prio=0 tid=0x00007f19c0126800 nid=0x3b82 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Finalizer" #3 daemon prio=8 os_prio=0 tid=0x00007f19c00fa800 nid=0x3b81 in Object.wait() [0x00007f198727c000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x0000000776289088> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
- locked <0x0000000776289088> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)
"Reference Handler" #2 daemon prio=10 os_prio=0 tid=0x00007f19c00f5800 nid=0x3b80 in Object.wait() [0x00007f198737d000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x0000000776280990> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:502)
at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
- locked <0x0000000776280990> (a java.lang.ref.Reference$Lock)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)
"VM Thread" os_prio=0 tid=0x00007f19c00ec000 nid=0x3b7f runnable
"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00007f19c006c000 nid=0x3b6d runnable
"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00007f19c006e000 nid=0x3b76 runnable
"GC task thread#2 (ParallelGC)" os_prio=0 tid=0x00007f19c0070000 nid=0x3b77 runnable
"GC task thread#3 (ParallelGC)" os_prio=0 tid=0x00007f19c0071800 nid=0x3b78 runnable
"GC task thread#4 (ParallelGC)" os_prio=0 tid=0x00007f19c0073800 nid=0x3b79 runnable
"GC task thread#5 (ParallelGC)" os_prio=0 tid=0x00007f19c0075800 nid=0x3b7a runnable
"GC task thread#6 (ParallelGC)" os_prio=0 tid=0x00007f19c0077000 nid=0x3b7d runnable
"GC task thread#7 (ParallelGC)" os_prio=0 tid=0x00007f19c0079000 nid=0x3b7e runnable
"VM Periodic Task Thread" os_prio=0 tid=0x00007f19c0148000 nid=0x3b88 waiting on condition
JNI global references: 313
【问题讨论】：
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你能在调试器中运行它并在它挂起时“中断”。根据堆栈跟踪，有些东西仍在运行并拒绝退出。你有每分钟左右醒来的线程吗？如果不使用调试器检查线程并查看它正在等待什么（具体检查 Object.wait() 线程，tryHandlePending 可能暗示它是尝试清理的 try 块的一部分）。
标签： java