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Subject: Re: cygserver - Postgres Multiple connection Load Testing - Inifinte Loop
References: <200408030333 DOT i733XEXn023894 AT mx3 DOT redhat DOT com> <20040803100612 DOT GP31522 AT cygbert DOT vinschen DOT de> <20170321025614 DOT GA2100214 AT tornado DOT leadboat DOT com> <20170324171101 DOT GI29995 AT calimero DOT vinschen DOT de> <20170328052652 DOT GA2351961 AT tornado DOT leadboat DOT com> <20170402023624 DOT GA2561924 AT tornado DOT leadboat DOT com> <20170507032747 DOT GA876495 AT rfd DOT leadboat DOT com>
To: cygwin AT cygwin DOT com
From: "Larry Hall (Cygwin)" <reply-to-list-only-lh AT cygwin DOT com>
Message-ID: <590E98DD.9000805@cygwin.com>
Date: Sat, 6 May 2017 23:47:41 -0400
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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.


-- 
Larry

_____________________________________________________________________

A: Yes.
 > 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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