Java very limited on max number of threads?

java multithreading memory memory-management profile
erotsppa picture erotsppa · Jul 5, 2010 · Viewed 10.6k times · Source

We have a small text box with 512Mb of ram. We wanted to see how many threads we can create in Java in this box. To our surprise, we can't create many. Essentially the minimum stack size you can set with -Xss is 64k. Simple math will tell you that 64*7000 will consume 430Mb so we were only able to get it up to around 7000 threads or so and then we encountered this error:

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

Is this the true limit with Java? Per 512Mb of ram we can only squeeze in 7k number of threads or so?

Answer

Tobias P. picture Tobias P. · Jul 5, 2010

Use asynchronous IO (java nio) and you'll don't need 7k threads to support 7k clients, a few threads for handling io (5?) will be enough.
Take a look at Netty ;)

One thread for each client is a really bad design.

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