From what Linux kernel/libc version is Java Runtime.exec() safe with regards to memory?

Question

At work one of our target platforms is a resource constrained mini-server running Linux (kernel 2.6.13, custom distribution based on an old Fedora Core). The application is writ

Answer 1

Yes, this absolutely is the case with even new versions of Linux (we're on 64-bit Red Hat 5.2). I have been having a problem with slow running subprocesses for about 18 months, and could never figure out the problem until I read your question and ran a test to verify it.

We have a 32 GB box with 16 cores, and if we run the JVM with settings like -Xms4g and -Xmx8g and run subprocesses using Runtime.exec() with 16 threads, we are not be able to run our process faster than about 20 process calls per second.

Try this with the simple "date" command in Linux about 10,000 times. If you add profiling code in to watch what is happening, it starts off quickly but slows down over time.

After reading your question, I decided to try lowering my memory settings to -Xms128m and -Xmx128m. Now our process runs at about 80 process calls per second. The JVM memory settings was all I changed.

It doesn't seem to be sucking up memory in such a way that I ever ran out of memory, even when I tried it with 32 threads. It's just the extra memory has to be allocated in some way, which causes a heavy startup (and maybe shutdown) cost.

Anyway, it seems like there should be a setting to disable this behavior Linux or maybe even in the JVM.