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Re: cygserver - Postgres Multiple connection Load Testing - Inifinte Loop
- From: Noah Misch <noah at leadboat dot com>
- To: cygwin at cygwin dot com
- Date: Sat, 6 May 2017 20:27:47 -0700
- Subject: Re: cygserver - Postgres Multiple connection Load Testing - Inifinte Loop
- Authentication-results: sourceware.org; auth=none
- References: <200408030333.i733XEXn023894@mx3.redhat.com> <20040803100612.GP31522@cygbert.vinschen.de> <20170321025614.GA2100214@tornado.leadboat.com> <20170324171101.GI29995@calimero.vinschen.de> <20170328052652.GA2351961@tornado.leadboat.com> <20170402023624.GA2561924@tornado.leadboat.com>
On Sat, Apr 01, 2017 at 10:36:24PM -0400, Noah Misch wrote:
> On Tue, Mar 28, 2017 at 01:26:52AM -0400, Noah Misch wrote:
> > On Fri, Mar 24, 2017 at 06:11:01PM +0100, Corinna Vinschen wrote:
> > > I pushed a patchset now, and uploaded new developer snapshots for
> > > testing to https://cygwin.com/snapshots/
> > > Please give it a try
> > I call the cygwin-20170324 freezes "limited" because the symptoms differ from
> > the classic freeze I described upthread. "strace /bin/true" and "cat
> > /proc/sysvipc/sem" do not hang, but every PostgreSQL backend process is stuck
> > waiting on a synchronization primitive.
> > I can distill another self-contained test case for the limited freeze seen in
> > cygwin-20170324, but that make take awhile. I'm sending this early report so
> > you're aware of the possible regression in cygwin-20170324.
> I'm attaching a new test program that demonstrates the regression. My previous
> test program created sixteen processes that each picked a random semaphore to
> lock. Now, each process picks two semaphores and locks them in order. This
> proceeds smoothly on GNU/Linux and on cygwin-20170321.tar.xz "cygserver -r 40".
> It freezes within one second on cygwin-20170324.tar.xz "cygserver -r 40".
I suggest reverting the cygwin-20170324 cygserver changes for now. Older
versions can be configured to have reliable sysv semaphores, but I think no
settings render sysv semaphores reliable in Cygwin 2.8.0. What do you think?
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