at threads.deadlock.DeadlockDemo$BadTransferOperation.transfer(DeadlockDemo.java:86)
- waiting to lock <7f3366e80> (a threads.deadlock.Account)
- locked <7f3366e98> (a threads.deadlock.Account)
at threads.deadlock.DeadlockDemo$BadTransferOperation.run(DeadlockDemo.java:59)
"Thread-7":
at threads.deadlock.DeadlockDemo$BadTransferOperation.transfer(DeadlockDemo.java:86)
- waiting to lock <7f3366eb0> (a threads.deadlock.Account)
- locked <7f3366e80> (a threads.deadlock.Account)
at threads.deadlock.DeadlockDemo$BadTransferOperation.run(DeadlockDemo.java:59)
"Thread-11":
at threads.deadlock.DeadlockDemo$BadTransferOperation.transfer(DeadlockDemo.java:86)
- waiting to lock <7f3366f58> (a threads.deadlock.Account)
- locked <7f3366eb0> (a threads.deadlock.Account)
at threads.deadlock.DeadlockDemo$BadTransferOperation.run(DeadlockDemo.java:59)
Found 1 deadlock.
Heap
par new generation total 19136K, used 11590K [7f3000000, 7f44c0000, 7f44c0000)
eden space 17024K, 68% used [7f3000000, 7f3b51ac0, 7f40a0000)
from space 2112K, 0% used [7f40a0000, 7f40a0000, 7f42b0000)
to space 2112K, 0% used [7f42b0000, 7f42b0000, 7f44c0000)
concurrent mark-sweep generation total 63872K, used 0K [7f44c0000, 7f8320000, 7fae00000)
concurrent-mark-sweep perm gen total 21248K, used 8268K [7fae00000, 7fc2c0000, 800000000)
Scanning quickly through, you can see that this thread dump is divided into four parts. These are:
A complete list of all the applcation’s threads
A list of deadlocked threads
A small stack trace of deadlocked threads
The application’s heap summary
The Thread List
The thread list in point one above is a list of all the application’s threads and their current status. From this you can see that an application consists of a whole bunch of threads, which you can roughly divide in to two. Firstly there are the background threads. These are the ones that every application has, which get on with all the dirty jobs that we, as application programmers, don’t usually need to worry about. These have names such as:"DestroyJavaVM", Low Memory Detector, Finalizer, Exception Catcher Thread andConcurrent Mark-Sweep GC Thread. Secondly, there are the threads that you or I may create as part of our code. These usually have names that consist of the wordThread followed by a number. For example: Thread-3, Thread-6 andThread-20.
"Thread-20" prio=5 tid=7f971216c000 nid=0x118c73000 waiting for monitor entry [118c72000]
java.lang.Thread.State: BLOCKED (on object monitor)
at threads.deadlock.DeadlockDemo$BadTransferOperation.transfer(DeadlockDemo.java:82)
- waiting to lock <7f3366e98> (a threads.deadlock.Account)
- locked <7f3366f58> (a threads.deadlock.Account)
at threads.deadlock.DeadlockDemo$BadTransferOperation.run(DeadlockDemo.java:58)
Looking at the information given on Thread-20 in more detail you can see that this can be broken down into several parts. These are:
Thread-20
The thread’s name as described above.
prio=5
The thread's priority. A number from 1 to 10, where 1 is the lowest and 10 is the highest priority.
tid=7f971216c000
The thread id. A unique number that’s returned by a Thread.getId() call.
nid=0x118c73000
The native thread id. This maps to a platform dependent thread id.
waiting for monitor entry [118c72000]
java.lang.Thread.State: BLOCKED (on object mon