On Mon, Sep 22, 2014 at 6:50 PM, Stephen Frost <[email protected]> wrote:
> Pavan, > > * Pavan Deolasee ([email protected]) wrote: > > On Thu, Sep 18, 2014 at 12:02 PM, Pavan Deolasee < > [email protected]> > > wrote: > > > While running some tests on REL9_2_STABLE branch, I saw an assertion > > > failure in syncrep.c. The stack trace looks like this: > > > > > Any comments on this? I see it very regularly during my pgbench tests. > > I agree that it looks like there may be a race condition there- but > could you provide the test cases you're working with? What kind of > behavior is it that's making it show up easily for you? > > Nothing special really. Set up a 2-node sync replication on my Mac laptop and running pgbench with 10 clients triggers it. As I said, after looking at the code and realising that there is a race condition, I tried with with gdb to reproduce the race I suspect. Anyways, the attached patch should trigger the race condition for a simple query. I'm deliberately making backend to wait to give walsender a chance to send outstanding WALs and then making walsender to wait so that assertion is triggered in the backend. Hope this helps. Thanks, Pavan -- Pavan Deolasee http://www.linkedin.com/in/pavandeolasee
syncrep_assertion_trigger.patch
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