Does Java blocked threads take up more CPU resources?

java multithreading cpu dump blocked
Oh Chin Boon picture Oh Chin Boon · May 5, 2011 · Viewed 8.9k times · Source

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.

Answer

Peter Lawrey picture Peter Lawrey · May 5, 2011

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.

Related questions

Which Java thread is hogging the CPU?

Let's say your Java program is taking 100% CPU. It has 50 threads. You need to find which thread is guilty. I have not found a tool that can help. Currently I use the following very time consuming routine: Run jstack <…

Read More
Throttling CPU/Memory usage of a Thread in Java?

I'm writing an application that will have multiple threads running, and want to throttle the CPU/memory usage of those threads. There is a similar question for C++, but I want to try and avoid using C++ and JNI if …

Read More
Threads configuration based on no. of CPU-cores

Scenario : I have a sample application and I have 3 different system configuration - - 2 core processor, 2 GB RAM, 60 GB HHD, - 4 core processor, 4 GB RAM, 80 GB HHD, - 8 core processor, 8 GB RAM, 120 GB HHD In order to effectively exploit the …

Read More