[libvirt] Entering freeze for libvirt-3.5.0

[Roman Bogorodskiy]

  Ján Tomko wrote:

> [cc: Guido]
> 
> On Sat, Jul 01, 2017 at 02:18:58PM +0400, Roman Bogorodskiy wrote:
> >  Andrea Bolognani wrote:
> >> virnetsockettest also fails pretty often for me, certainly
> >> more than your figure; even if that wasn't the case, 1/5
> >> failure rate is way too high for a CI job.
> >
> >I played a little more with virnetsockettest to get real stats and
> >figured the following:
> >
> > 1. On my desktop (i5) and laptop (i3), I didn't get any failures in 50
> > 'check' runs
> > 2. On a VM that I use to run test builds in Jenkins, out of 50 runs it
> > fails from 1 to 6 times; I did this test a couple of times and either I
> > was lucky or failure rate is higher when my Jenkins perform regular
> > builds.
> >
> >Anyway, I'll try to find a way to debug what's going on with
> >virnetsockettest.
> >
> 
> IIRC Debian disabled this test years ago.
> 
> Guido, have you ever discovered the cause?
> 
> Jan

I made some experiments on the weekend, and here are my results:

On a box where test fails from time to time, it fails at this point:

    virObjectUnref(csock);

    for (i = 0; i < nlsock; i++) {
        if (virNetSocketAccept(lsock[i], &ssock) != -1 && ssock) {
            char c = 'a';
            if (virNetSocketWrite(ssock, &c, 1) != -1 &&
                virNetSocketRead(ssock, &c, 1) != -1) {
                VIR_DEBUG("Unexpected client socket present"); <--- HERE
                goto cleanup;
            }   
        }   
        virObjectUnref(ssock);
        ssock = NULL;
    }  

On a box where this test never fails, it reaches this block, but:

 * virNetSocketWrite(ssock, &c, 1) != -1
 * virNetSocketRead(ssock, &c, 1) == -1

It's enough to make the test pass. On a failing box both Write() and Read()
return != -1 when the test fails. 

I'm not quite sure what this specific block is testing though. My guess
was that calling "virObjectUnref(csock);" will destroy the client socket
and Accept() will not work (this should also make the test pass I
guess).

Anyway, I tried to insert sleep(1) right after virObjectUnref(csock),
the one before the virNetSocketAccept() call,
and the test stopped failing. I've started it in a loop like:

 while test $? -eq 0; do ./virnetsockettest; done

and actually forgot to stop, so it's running since Saturday without
failures.

I've haven't had a chance yet to debug it further.

Roman Bogorodskiy
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