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Re: errors with high connections rate

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On 07/03/2012 04:26 PM, Pawel S. Veselov wrote:

That's the thing, no segfaults (dmesg), nothing in the server logs.

It may as well be some sort of an anti-fork-bomb measure, only judging by the fact that with enough attempts, things do clear out, though I wish there would be some indication of that, and I'm still confused about the error code being ENOTCONN.


I've managed to produce the endpoint not connected errors with a little test I wrote here. Only once so far and only during an abnormal test run where I signalled the test workers as they were starting up, so that's not really very helpful.

I have no problem using a little Python test program to create 800 connections in about a second. It forks some workers (100 by default) which grab enough connections each to reach the target connection count.

Ooh, handy. I just triggered it again now. The "Transport endpoint is not connected" messages were intermixed with some "FATAL: sorry, too many clients already" messages. The PostgreSQL log is full of FATAL: sorry, too many clients already" messages intermixed with "LOG: unexpected EOF on client connection" messages. Again it was an abnormal run where I signalled my workers mid way through startup.

Interesting, that. I've never seen it on a run where I don't send a signal. You know what that makes me think? You're using a multithreaded approach, and there's something going wrong in your app's innards. Yes, that's a lot of hot air and handwaving, but it fits - you're getting an error saying that psql is trying to operate on a socket that isn't there.

The fact that there's nothing in the system logs or Pg logs just adds weight to that. I'm guessing you have a threading bug, possibly signal related.

--
Craig Ringer

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