java.lang.OutOfMemoryError: unable to create new native thread

In JVM, each thread is allocated separate memory space called "thread stack", which is configured by JVM option "-Xss". The default value depends on OS/JVM. As number of threads increase, memory usage increases and can lead to 'out ofMemoryError'. Remember, the memory for threads is allocated on stack and not on Java Heap.

Solution:

If you are getting this error, then you can try decreasing the memory allocated to heap (-Xmx) and/or decreasing the thread stack memory (-Xss). Increasing -Xmx (32bit systems) will leave less room for threads if it is being used, hence the opposite of the solution.

Remember the memory allocated using '-Xss' is the maximum memory allocated per thread, and usually it's in KB. Also too low -Xss value can cause java.lang.StackOverflowError. If you continue to get the same error, you probably have thread leak, fix the program.