Random Linux SERVER hangups production

Well, surely there are bugs in my program. We find them sometimes, although not as often as when it went to production the first time.

That said, it is a userspace program. It uses system resources only to read-write to files and send messages over TCP connections. It runs as a non root user.

The issue is that this userpace program hangs the operating system in some weird way (or, possibly, that the OS problems are unrelated to my userspace program).

I mentioned the symptoms, which is some things become messed up, for instance I cannot tail its logfile with "-usr-bin-tail", or that sshd can no longer fully initialize a session (it logs the user on, says "starting interactive session" and hangs up).

Again, not everything becomes broken -- it is not a hard freeze -- but it is bad enough to need a reboot.

As far as distro goes, my app does not use any functionality beyond which is provided by the kernel. It is not something funky like read from a TV card and write to a USB wireless gadget while streaming sound to two sound cards. It is the bread and butter of computing, reading-writing to files and ethernet network.

I would not be here asking if it was a simple problem. Hence, I am looking for some reasoned answers, not for comments like "Fedora

I have reasons to suspect that it is my app that causes system problems: it happens on two machines running my app that have different distros installed. That said, neither its memory usage (144 Mb) not its file usage are unusual, although I do have perhaps 200 fds open. But 200 fds is nothing outrageous and should be handled fine by linux.

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