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Re: cygserver - Postgres Multiple connection Load Testing - Inifinte Loop


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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