OS X Java maximum threads per process

Question

Running this code

        for (int i = 0; i < 4000; i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(60000);
                    } catch (InterruptedException e) {
                    }
                }
            }).start();
            System.out.println(i);
        }

results in

Exception in thread "main" java.lang.OutOfMemoryError: unable to create new native thread
    at java.lang.Thread.start0(Native Method)
    at java.lang.Thread.start(Thread.java:658)
    at com.codeoverdrive.burnbearburn.Main.main(Main.java:10)

after 2024 running threads. Playing with JVM heap and stack sizes does not help.

sysctl kern.num_threads

returns

kern.num_threads: 10240

OS X Mountain Lion 10.8.4, Macbook Air with 4GB RAM

Any suggestions?

@fge increasing permgen does not help because it is used for class definitions and associated metadata. — mixel, Jun 13 '13 at 09:22

score 3 · Answer 1 · answered Jun 13 '13 at 09:24

3

The most probable cause is that the user you are running with has a limit on the number of threads it can create.

Try and increase this limit. The current limit can be shown by the ulimit -u command. Note that as a regular user you probably won't be able to increase it, you'll have to modify the environment as root.

And yes, OutOfMemoryError is misleading in this case.

answered Jun 13 '13 at 09:24

fge

119,121
33
254
329

`ulimit -u` shows max users processes count, not threads. And I do not know why, but setting it does not changes it's value. – mixel Jun 13 '13 at 09:35
It also influences the number of threads! At least on Linux it does. And yes, it is normal that you cannot change it as a user. – fge Jun 13 '13 at 09:44

OS X Java maximum threads per process

1 Answers1