主线程没有调用堆栈的 Java 线程转储？ (jsvc)

Question

我们有一个作为守护进程运行的 java 进程(在 jsvc 下)。每隔几天它就会停止做任何工作；日志文件的输出停止(非常冗长，每隔 5 分钟)并且不消耗 CPU 或 IO。

日志文件、syserr 或 sysout 中都没有记录异常。最后一条日志语句是在数据库提交之前完成的，但是数据库服务器(MySQL)上没有打开连接并查看代码，之后应该总是有额外的日志输出，即使它遇到了异常会冒泡。

我发现最奇怪的是，在线程转储(包括在下面)中，我们的代码中根本没有线程，而且主线程似乎没有任何上下文:

"main" prio=10 tid=0x0000000000614000 nid=0x445d runnable [0x0000000000000000]
  java.lang.Thread.State: RUNNABLE

如前所述，这是一个使用 jsvc 运行的守护进程，但我不知道这是否与它有关(我可以重组代码以允许直接运行它，以进行测试)。

对这里可能发生的事情有什么建议吗？

谢谢...dwh

完整线程转储:

Full thread dump Java HotSpot(TM) 64-Bit Server VM (14.2-b01 mixed mode):

"MySQL Statement Cancellation Timer" daemon prio=10 tid=0x00002aaaf81b8800 nid=0x447b in Object.wait() [0x00002aaaf6a22000]
   java.lang.Thread.State: WAITING (on object monitor)
 at java.lang.Object.wait(Native Method)
 - waiting on <0x00002aaab5556d50> (a java.util.TaskQueue)
 at java.lang.Object.wait(Object.java:485)
 at java.util.TimerThread.mainLoop(Timer.java:483)
 - locked <0x00002aaab5556d50> (a java.util.TaskQueue)
 at java.util.TimerThread.run(Timer.java:462)

"Low Memory Detector" daemon prio=10 tid=0x00000000006a4000 nid=0x4479 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"CompilerThread1" daemon prio=10 tid=0x00000000006a1000 nid=0x4477 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"CompilerThread0" daemon prio=10 tid=0x000000000069d000 nid=0x4476 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" daemon prio=10 tid=0x000000000069b000 nid=0x4465 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" daemon prio=10 tid=0x0000000000678800 nid=0x4464 in Object.wait() [0x00002aaaf61d6000]
   java.lang.Thread.State: WAITING (on object monitor)
 at java.lang.Object.wait(Native Method)
 - waiting on <0x00002aaab54a1cb8> (a java.lang.ref.ReferenceQueue$Lock)
 at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:118)
 - locked <0x00002aaab54a1cb8> (a java.lang.ref.ReferenceQueue$Lock)
 at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:134)
 at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159)

"Reference Handler" daemon prio=10 tid=0x0000000000676800 nid=0x4463 in Object.wait() [0x00002aaaf60d5000]
   java.lang.Thread.State: WAITING (on object monitor)
 at java.lang.Object.wait(Native Method)
 - waiting on <0x00002aaab54a1cf0> (a java.lang.ref.Reference$Lock)
 at java.lang.Object.wait(Object.java:485)
 at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)
 - locked <0x00002aaab54a1cf0> (a java.lang.ref.Reference$Lock)

"main" prio=10 tid=0x0000000000614000 nid=0x445d runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"VM Thread" prio=10 tid=0x0000000000670000 nid=0x4462 runnable 

"GC task thread#0 (ParallelGC)" prio=10 tid=0x000000000061e000 nid=0x445e runnable 

"GC task thread#1 (ParallelGC)" prio=10 tid=0x0000000000620000 nid=0x445f runnable 

"GC task thread#2 (ParallelGC)" prio=10 tid=0x0000000000622000 nid=0x4460 runnable 

"GC task thread#3 (ParallelGC)" prio=10 tid=0x0000000000623800 nid=0x4461 runnable 

"VM Periodic Task Thread" prio=10 tid=0x00000000006a6800 nid=0x447a waiting on condition 

JNI global references: 797

Heap
 PSYoungGen      total 162944K, used 48388K [0x00002aaadff40000, 0x00002aaaf2ab0000, 0x00002aaaf5490000)
  eden space 102784K, 47% used [0x00002aaadff40000,0x00002aaae2e81170,0x00002aaae63a0000)
  from space 60160K, 0% used [0x00002aaaeb850000,0x00002aaaeb850000,0x00002aaaef310000)
  to   space 86720K, 0% used [0x00002aaae63a0000,0x00002aaae63a0000,0x00002aaaeb850000)
 PSOldGen        total 699072K, used 699072K [0x00002aaab5490000, 0x00002aaadff40000, 0x00002aaadff40000)
  object space 699072K, 100% used [0x00002aaab5490000,0x00002aaadff40000,0x00002aaadff40000)
 PSPermGen       total 21248K, used 9252K [0x00002aaab0090000, 0x00002aaab1550000, 0x00002aaab5490000)
  object space 21248K, 43% used [0x00002aaab0090000,0x00002aaab09993e8,0x00002aaab1550000)

Answer 1

并非所有 Throwable 都是异常。您的错误记录代码是否捕获错误(OutOfMemoryError、StackOverflowError 等)？