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Re: cygserver - Postgres Multiple connection Load Testing - Inifinte Loop
- From: "Larry Hall (Cygwin)" <reply-to-list-only-lh at cygwin dot com>
- To: cygwin at cygwin dot com
- Date: Sat, 6 May 2017 23:47:41 -0400
- 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> <20170507032747.GA876495@rfd.leadboat.com>
- Reply-to: cygwin at cygwin dot com
On 05/06/2017 11:27 PM, Noah Misch wrote:
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?
Just FYI, Corinna is away for a bit (in European time, "a bit" = until
June ;-) ) so don't be surprised if her response is delayed.
> Q: Are you sure?
>> A: Because it reverses the logical flow of conversation.
>>> Q: Why is top posting annoying in email?
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