Java Thread 那些事(三)

Found one Java-level deadlock:
=============================
"withdraw":
  waiting to lock monitor 0x00007f3400003620 (object 0x00000000d7fae540, a java.lang.Object),
  which is held by "deposit"
"deposit":
  waiting to lock monitor 0x00007f3400004b20 (object 0x00000000d7fae530, a java.lang.Object),
  which is held by "withdraw"

Java stack information for the threads listed above:
===================================================
"withdraw":
	at com.von.thread.research.DeadThread.depositMoney(DeadThread.java:13)
	- waiting to lock <0x00000000d7fae540> (a java.lang.Object)
	- locked <0x00000000d7fae530> (a java.lang.Object)
	at com.von.thread.research.DeadThread.run(DeadThread.java:28)
	at java.lang.Thread.run(Thread.java:724)
"deposit":
	at com.von.thread.research.DeadThread.withdrawMoney(DeadThread.java:21)
	- waiting to lock <0x00000000d7fae530> (a java.lang.Object)
	- locked <0x00000000d7fae540> (a java.lang.Object)
	at com.von.thread.research.DeadThread.run(DeadThread.java:29)
	at java.lang.Thread.run(Thread.java:724)

Found 1 deadlock.

这里是一个非顺序加锁诱发的一个死锁场景。

好了，差不多了。 总结一下，在调优过程中，重点关注以下三类情况：

1. waiting for monitor entry thread state blocked。可能发生的问题: deadlock（sequential deadlock，starvation deadlock...）
2. waiting on condition sleeping or timed_waiting。可能发生的问题: IO bottleneck
3. Object.wait TIMED_WAITING。问题：wait & notifyAll使用上需要明确其性能及其局限性问题。External锁，更多的考虑使用await和singal方法。

参考文献：

http://architects.dzone.com/articles/how-analyze-java-thread-dumps

http://stackoverflow.com/questions/7698861/simple-java-example-runs-with-14-threads-why

http://www.longene.org/forum/viewtopic.php f=5&t=94&p=399#p399

http://www.slideshare.net/Byungwook/analysis-bottleneck-in-j2ee-application

http://docs.oracle.com/javase/1.5.0/docs/guide/misc/threadPrimitiveDeprecation.html

JavaConcurrency in practice