Re: Assertion failure in syncrep.c
| От | Pavan Deolasee |
|---|---|
| Тема | Re: Assertion failure in syncrep.c |
| Дата | |
| Msg-id | CABOikdMn_aoDFVYTYJGe-V-=iePfCK3Qu61YyO_Y=+vwdTOxvQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Assertion failure in syncrep.c (Stephen Frost <sfrost@snowman.net>) |
| Ответы |
Re: Assertion failure in syncrep.c
|
| Список | pgsql-hackers |
On Mon, Sep 22, 2014 at 6:50 PM, Stephen Frost <sfrost@snowman.net> wrote:
Pavan,
* Pavan Deolasee (pavan.deolasee@gmail.com) wrote:
> On Thu, Sep 18, 2014 at 12:02 PM, Pavan Deolasee <pavan.deolasee@gmail.com>
> 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
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