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javamultithreadingcpudumpblocked-threads

Does Java blocked threads take up more CPU resources?

i would like to ask if Java will utilize more CPU resources when threads are blocked, i.e. waiting to lock a monitor which is currently being locked by another thread.

I am now looking at a thread dump whereby some threads are blocked as they are waiting to lock a monitor, and i am unsure if that is what may be accountable for the high CPU usage.

Thanks!

EDIT (6 May 2011) I forgot to mention if this behavior is relevant for Java SE 1.4.2.

Solution

  • Threads consume resources such as memory. A blocking/unblocking thread incurs a once off cost. If a thread blocking/unblocks tens of thousands of times per second this can waste significant amounts of CPU.

    However once a thread is blocked, it doesn't matter how long it is blocked for, there is no ongoing cost.