System.err（）上的Java线程锁

我有点困惑

我有两个线程写入System.err和System.out，最终它们被困在线程锁中。System.err和System.out真的不是线程安全的吗

此时程序的结构为：

主线程启动了两个读线程来进行一些处理和打印输出，通过ThreadPoolExecutor调用。 一个读卡器线程s3gp-2，在名为IOStats.add的同步方法中，在单独的IOStats对象中的System.err.format上被阻止。 另一个被正确阻止的读卡器线程试图调用System.err.format上被阻止的同一IOStats.add方法。 请注意，每个读卡器通常都会写入System.err和System.out

我应该有一个单独的单例对象，用同步方法处理所有输出吗？如往常一样，非常感谢您的任何见解

更新

我意识到我应该给出更多的上下文：java程序由Greenplum DB的所有n段通过一个create外部web表并行调用。。。执行prgm。这种锁定行为非常罕见，而且通常都很顺利。当问题发生时，所有n个进程都被阻塞。我只关注其中一个用于调试

还有一些注意事项：

有几分钟，我认为我也使用log4j.Logger可能会引起麻烦。但是，事实上，该程序没有使用控制台appender，所以我不太倾向于认为这是问题所在。 通过使用lsof和ls-l/proc/$pid/fd，我观察到java进程的stderr被阻塞在一个同样由postgres读取的管道中。正如一位评论者所说，这可能是因为这条管道实际上并没有被postgres排空，这会阻止System.err打印输出。 事实上，以下是相关内容：

% lsof | head -1
COMMAND     PID      USER   FD      TYPE             DEVICE       SIZE       NODE NAME
% lsof | grep $pid | grep ' 2w '
java      10047   gpadmin    2w     FIFO                0,6              26854739 pipe
% lsof | grep $pid | grep ' 2w '
java      10047   gpadmin    2w     FIFO                0,6              26854739 pipe
% node=26854739
% lsof | grep $node
postgres  10028   gpadmin   26r     FIFO                0,6              26854739 pipe
sh        10046   gpadmin    2w     FIFO                0,6              26854739 pipe
java      10047   gpadmin    2w     FIFO                0,6              26854739 pipe

详细信息：堆栈转储jstack-l pid为我提供：

2012-04-17 12:23:02
Full thread dump Java HotSpot(TM) 64-Bit Server VM (21.0-b17 mixed mode):

"Attach Listener" daemon prio=10 tid=0x00000000061a3800 nid=0x75c5 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

   Locked ownable synchronizers:
    - None

"s3gp-2" prio=10 tid=0x00002aaabc207000 nid=0x281f runnable [0x0000000041718000]
   java.lang.Thread.State: RUNNABLE
    at java.io.FileOutputStream.writeBytes(Native Method)
    at java.io.FileOutputStream.write(FileOutputStream.java:318)
    at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
    at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
    - locked <0x00000000f601c4f8> (a java.io.BufferedOutputStream)
    at java.io.PrintStream.write(PrintStream.java:482)
    - locked <0x00000000f601c4d8> (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 <0x00000000f601c6f0> (a java.io.OutputStreamWriter)
    at java.io.OutputStreamWriter.flushBuffer(OutputStreamWriter.java:185)
    at java.io.PrintStream.write(PrintStream.java:527)
    - locked <0x00000000f601c4d8> (a java.io.PrintStream)
    at java.io.PrintStream.print(PrintStream.java:669)
    at java.io.PrintStream.append(PrintStream.java:1065)
    at java.io.PrintStream.append(PrintStream.java:57)
    at java.util.Formatter$FixedString.print(Formatter.java:2563)
    at java.util.Formatter.format(Formatter.java:2476)
    at java.io.PrintStream.format(PrintStream.java:970)
    - locked <0x00000000f601c4d8> (a java.io.PrintStream)
    at com.foo.serv.util.Loader$IOStats.add(Loader.java:136)
    - locked <0x00000000f6015870> (a com.foo.serv.util.Loader$IOStats)
    at com.foo.serv.util.Loader$Reader.run(Loader.java:199)
    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:
    - <0x00000000f6024470> (a java.util.concurrent.ThreadPoolExecutor$Worker)

"s3gp-1" prio=10 tid=0x00002aaabc1fa000 nid=0x281e waiting for monitor entry [0x00000000405d9000]
   java.lang.Thread.State: BLOCKED (on object monitor)
    at com.foo.serv.util.Loader$IOStats.add(Loader.java:129)
    - waiting to lock <0x00000000f6015870> (a com.foo.serv.util.Loader$IOStats)
    at com.foo.serv.util.Loader$Reader.run(Loader.java:199)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)

   Locked ownable synchronizers:
    - <0x00000000f601ea50> (a java.util.concurrent.ThreadPoolExecutor$Worker)

"Service Thread" daemon prio=10 tid=0x00002aaab0054000 nid=0x27e7 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

   Locked ownable synchronizers:
    - None

"C2 CompilerThread1" daemon prio=10 tid=0x00002aaab0051800 nid=0x27e6 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

   Locked ownable synchronizers:
    - None

"C2 CompilerThread0" daemon prio=10 tid=0x00002aaab004e800 nid=0x27e4 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

   Locked ownable synchronizers:
    - None

"Signal Dispatcher" daemon prio=10 tid=0x00002aaab004c000 nid=0x27e3 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

   Locked ownable synchronizers:
    - None

"Finalizer" daemon prio=10 tid=0x00002aaab0001000 nid=0x2762 in Object.wait() [0x00000000428cc000]
   java.lang.Thread.State: WAITING (on object monitor)
    at java.lang.Object.wait(Native Method)
    - waiting on <0x00000000f6015730> (a java.lang.ref.ReferenceQueue$Lock)
    at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
    - locked <0x00000000f6015730> (a java.lang.ref.ReferenceQueue$Lock)
    at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
    at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:177)

   Locked ownable synchronizers:
    - None

"Reference Handler" daemon prio=10 tid=0x0000000005edc800 nid=0x2760 in Object.wait() [0x00000000427cb000]
   java.lang.Thread.State: WAITING (on object monitor)
    at java.lang.Object.wait(Native Method)
    - waiting on <0x00000000f603b9c0> (a java.lang.ref.Reference$Lock)
    at java.lang.Object.wait(Object.java:503)
    at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)
    - locked <0x00000000f603b9c0> (a java.lang.ref.Reference$Lock)

   Locked ownable synchronizers:
    - None

"main" prio=10 tid=0x0000000005e3f800 nid=0x2744 waiting on condition [0x0000000041abe000]
   java.lang.Thread.State: TIMED_WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000f61df188> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:226)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2082)
    at java.util.concurrent.ThreadPoolExecutor.awaitTermination(ThreadPoolExecutor.java:1433)
    at com.foo.serv.util.Loader.execute(Loader.java:107)
    at com.foo.serv.util.Loader.main(Loader.java:571)

   Locked ownable synchronizers:
    - None

"VM Thread" prio=10 tid=0x0000000005ed5000 nid=0x275e runnable

"GC task thread#0 (ParallelGC)" prio=10 tid=0x0000000005e4a000 nid=0x2745 runnable

"GC task thread#1 (ParallelGC)" prio=10 tid=0x0000000005e4c000 nid=0x2746 runnable

"GC task thread#2 (ParallelGC)" prio=10 tid=0x0000000005e4e000 nid=0x2747 runnable

"GC task thread#3 (ParallelGC)" prio=10 tid=0x0000000005e4f800 nid=0x2748 runnable

"GC task thread#4 (ParallelGC)" prio=10 tid=0x0000000005e51800 nid=0x2749 runnable

"GC task thread#5 (ParallelGC)" prio=10 tid=0x0000000005e53800 nid=0x274a runnable

"GC task thread#6 (ParallelGC)" prio=10 tid=0x0000000005e55000 nid=0x274b runnable

"GC task thread#7 (ParallelGC)" prio=10 tid=0x0000000005e57000 nid=0x274c runnable

"GC task thread#8 (ParallelGC)" prio=10 tid=0x0000000005e59000 nid=0x274d runnable

"GC task thread#9 (ParallelGC)" prio=10 tid=0x0000000005e5b000 nid=0x274e runnable

"GC task thread#10 (ParallelGC)" prio=10 tid=0x0000000005e5c800 nid=0x274f runnable

"GC task thread#11 (ParallelGC)" prio=10 tid=0x0000000005e5e800 nid=0x2750 runnable

"GC task thread#12 (ParallelGC)" prio=10 tid=0x0000000005e60800 nid=0x2751 runnable

"VM Periodic Task Thread" prio=10 tid=0x00002aaab005e800 nid=0x27eb waiting on condition

JNI global references: 207

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所以System.err和System.out不是您的问题。基础PrintStream对象已同步。您根本不需要对它们执行任何锁定。@JohnVint System.err是一个PrintStream.1。您是否有可能正在运行一个无止境的循环，并且System.err不是真正的阻塞？相关的代码示例将帮助我们提前消除这些假设。2.System.err是否有可能重定向到实际上可以阻止的接收器？请允许我指出，您没有死锁的情况，但是I/O阻塞您的线程是可运行的。System.err和System.out通常会填充缓冲区，当内容流式传输到文件时，缓冲区会被其他进程（如控制台或操作系统）耗尽。你是否已将他们重定向到需要排空的地方？这是在同一个进程中发生的吗？看起来System.err的目标已满，而不是Java中的线程问题