Deadlocks

If every thread is waiting to enter monitors that are owned by another thread, the system runs into a deadlock situation. A thread/monitor dump is what programmers need to find the cause of this kind of deadlocks.¹ A thread/monitor dump includes the following information:

• The stack trace of all threads.
• The owner of each monitor and the list of threads that are waiting to enter the monitor.

To obtain a consistent view of all threads and all monitors, we suspend all threads when collecting thread/monitor dumps. The JDK has historically provided support for thread/monitor dumps triggered by special key sequences (such as Ctrl-Break on Win32). The JVMPI now allows the profiler agent to obtain the same information programmatically.