使用wiki-java时很少遇到死锁。看一下完整的线程转储（通过kill -3 $JAVA-PID获得）表明死锁似乎是源自SSLSocketImpl中的某个地方。我宁愿首先避免这种僵局（而不是做一些hacky恢复），但我不确定如何找到原因并阻止它。有没有办法在SSLSocketImpl中设置超时或在死锁的情况下抛出异常？ （在主循环中捕获它并重做最后一次调用会非常简单）
Full thread dump OpenJDK 64-Bit Server VM (24.51-b03 mixed mode):
"Service Thread" daemon prio=10 tid=0x00007f3cd816b000 nid=0x102c runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread1" daemon prio=10 tid=0x00007f3cd8168800 nid=0x102b waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" daemon prio=10 tid=0x00007f3cd8165800 nid=0x102a waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Signal Dispatcher" daemon prio=10 tid=0x00007f3cd8163800 nid=0x1029 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Finalizer" daemon prio=10 tid=0x00007f3cd8140800 nid=0x1028 waiting on condition [0x00007f3ccb9f7000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000007d77a9080> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:867)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1197)
at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:214)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:290)
at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:799)
at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:672)
at sun.security.ssl.SSLSocketImpl.sendAlert(SSLSocketImpl.java:2005)
at sun.security.ssl.SSLSocketImpl.warning(SSLSocketImpl.java:1832)
at sun.security.ssl.SSLSocketImpl.closeInternal(SSLSocketImpl.java:1600)
- locked <0x00000007d77a8d78> (a sun.security.ssl.SSLSocketImpl)
at sun.security.ssl.SSLSocketImpl.close(SSLSocketImpl.java:1538)
at sun.security.ssl.BaseSSLSocketImpl.finalize(BaseSSLSocketImpl.java:249)
at java.lang.ref.Finalizer.invokeFinalizeMethod(Native Method)
at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:101)
at java.lang.ref.Finalizer.access$100(Finalizer.java:32)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:190)
"Reference Handler" daemon prio=10 tid=0x00007f3cd813e800 nid=0x1027 in Object.wait() [0x00007f3ccbaf9000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x000000078495a2c8> (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 <0x000000078495a2c8> (a java.lang.ref.Reference$Lock)
"main" prio=10 tid=0x00007f3cd8008000 nid=0x1021 waiting for monitor entry [0x00007f3cdfdb7000]
java.lang.Thread.State: BLOCKED (on object monitor)
at sun.security.ssl.SSLSocketImpl.getConnectionState(SSLSocketImpl.java:649)
- waiting to lock <0x00000007d77a8d78> (a sun.security.ssl.SSLSocketImpl)
at sun.security.ssl.SSLSocketImpl.isClosed(SSLSocketImpl.java:1446)
at java.net.Socket.getTcpNoDelay(Socket.java:965)
at sun.security.ssl.BaseSSLSocketImpl.getTcpNoDelay(BaseSSLSocketImpl.java:345)
at sun.security.ssl.SSLSocketImpl.writeRecordInternal(SSLSocketImpl.java:819)
at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:801)
at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:122)
- locked <0x00000007d77a8d60> (a sun.security.ssl.AppOutputStream)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
- locked <0x00000007d77a8d48> (a java.io.BufferedOutputStream)
at java.io.PrintStream.flush(PrintStream.java:338)
- locked <0x00000007d77a8d28> (a java.io.PrintStream)
at sun.net.www.MessageHeader.print(MessageHeader.java:297)
- locked <0x00000007d6d057b0> (a sun.net.www.MessageHeader)
at sun.net.www.http.HttpClient.writeRequests(HttpClient.java:599)
at sun.net.www.http.HttpClient.writeRequests(HttpClient.java:610)
at sun.net.www.protocol.http.HttpURLConnection.writeRequests(HttpURLConnection.java:619)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1321)
- locked <0x00000007d6d05640> (a sun.net.www.protocol.https.DelegateHttpsURLConnection)
at sun.net.www.protocol.http.HttpURLConnection.getHeaderFieldKey(HttpURLConnection.java:2731)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getHeaderFieldKey(HttpsURLConnectionImpl.java:307)
at shared.Wiki.grabCookies(Wiki.java:6907)
at shared.Wiki.fetch(Wiki.java:6462)
at shared.Wiki.getPageText(Wiki.java:1465)
at smallBots.Bot1.getText(Bot1.java:204)
at smallBots.Bot1.crawlCategory(Bot1.java:74)
at smallBots.Bot1.main(Bot1.java:49)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)
"VM Thread" prio=10 tid=0x00007f3cd813a000 nid=0x1026 runnable
"GC task thread#0 (ParallelGC)" prio=10 tid=0x00007f3cd801d800 nid=0x1022 runnable
"GC task thread#1 (ParallelGC)" prio=10 tid=0x00007f3cd801f800 nid=0x1023 runnable
"GC task thread#2 (ParallelGC)" prio=10 tid=0x00007f3cd8021800 nid=0x1024 runnable
"GC task thread#3 (ParallelGC)" prio=10 tid=0x00007f3cd8023000 nid=0x1025 runnable
"VM Periodic Task Thread" prio=10 tid=0x00007f3cd8175800 nid=0x102d waiting on condition
JNI global references: 205
Found one Java-level deadlock:
=============================
"Finalizer":
waiting for ownable synchronizer 0x00000007d77a9080, (a java.util.concurrent.locks.ReentrantLock$NonfairSync),
which is held by "main"
"main":
waiting to lock monitor 0x00007f3cac0015c8 (object 0x00000007d77a8d78, a sun.security.ssl.SSLSocketImpl),
which is held by "Finalizer"
Java stack information for the threads listed above:
===================================================
"Finalizer":
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000007d77a9080> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:867)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1197)
at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:214)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:290)
at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:799)
at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:672)
at sun.security.ssl.SSLSocketImpl.sendAlert(SSLSocketImpl.java:2005)
at sun.security.ssl.SSLSocketImpl.warning(SSLSocketImpl.java:1832)
at sun.security.ssl.SSLSocketImpl.closeInternal(SSLSocketImpl.java:1600)
- locked <0x00000007d77a8d78> (a sun.security.ssl.SSLSocketImpl)
at sun.security.ssl.SSLSocketImpl.close(SSLSocketImpl.java:1538)
at sun.security.ssl.BaseSSLSocketImpl.finalize(BaseSSLSocketImpl.java:249)
at java.lang.ref.Finalizer.invokeFinalizeMethod(Native Method)
at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:101)
at java.lang.ref.Finalizer.access$100(Finalizer.java:32)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:190)
"main":
at sun.security.ssl.SSLSocketImpl.getConnectionState(SSLSocketImpl.java:649)
- waiting to lock <0x00000007d77a8d78> (a sun.security.ssl.SSLSocketImpl)
at sun.security.ssl.SSLSocketImpl.isClosed(SSLSocketImpl.java:1446)
at java.net.Socket.getTcpNoDelay(Socket.java:965)
at sun.security.ssl.BaseSSLSocketImpl.getTcpNoDelay(BaseSSLSocketImpl.java:345)
at sun.security.ssl.SSLSocketImpl.writeRecordInternal(SSLSocketImpl.java:819)
at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:801)
at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:122)
- locked <0x00000007d77a8d60> (a sun.security.ssl.AppOutputStream)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
- locked <0x00000007d77a8d48> (a java.io.BufferedOutputStream)
at java.io.PrintStream.flush(PrintStream.java:338)
- locked <0x00000007d77a8d28> (a java.io.PrintStream)
at sun.net.www.MessageHeader.print(MessageHeader.java:297)
- locked <0x00000007d6d057b0> (a sun.net.www.MessageHeader)
at sun.net.www.http.HttpClient.writeRequests(HttpClient.java:599)
at sun.net.www.http.HttpClient.writeRequests(HttpClient.java:610)
at sun.net.www.protocol.http.HttpURLConnection.writeRequests(HttpURLConnection.java:619)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1321)
- locked <0x00000007d6d05640> (a sun.net.www.protocol.https.DelegateHttpsURLConnection)
at sun.net.www.protocol.http.HttpURLConnection.getHeaderFieldKey(HttpURLConnection.java:2731)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getHeaderFieldKey(HttpsURLConnectionImpl.java:307)
at shared.Wiki.grabCookies(Wiki.java:6907)
at shared.Wiki.fetch(Wiki.java:6462)
at shared.Wiki.getPageText(Wiki.java:1465)
at smallBots.Bot1.getText(Bot1.java:204)
at smallBots.Bot1.crawlCategory(Bot1.java:74)
at smallBots.Bot1.main(Bot1.java:49)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)
Found 1 deadlock.
Heap
PSYoungGen total 10752K, used 801K [0x00000007d6d00000, 0x00000007d7880000, 0x0000000800000000)
eden space 9728K, 1% used [0x00000007d6d00000,0x00000007d6d1fc20,0x00000007d7680000)
from space 1024K, 65% used [0x00000007d7780000,0x00000007d7828b40,0x00000007d7880000)
to space 1024K, 0% used [0x00000007d7680000,0x00000007d7680000,0x00000007d7780000)
ParOldGen total 93696K, used 69956K [0x0000000784800000, 0x000000078a380000, 0x00000007d6d00000)
object space 93696K, 74% used [0x0000000784800000,0x0000000788c51160,0x000000078a380000)
PSPermGen total 21504K, used 9537K [0x000000077a200000, 0x000000077b700000, 0x0000000784800000)
object space 21504K, 44% used [0x000000077a200000,0x000000077ab50720,0x000000077b700000)
答案 0 :(得分：1)
提问者回答：更新到Java 8以修复它。