On Mon, Oct 31, 2016 at 10:32 AM, Oskari Saarenmaa <o...@ohmu.fi> wrote:
> 27.10.2016, 21:53, Merlin Moncure kirjoitti:
>> As noted earlier, I was not able to reproduce the issue with
>> crashme.sh, which was:
>> do_parallel psql -p 5432  -c"select PushMarketSample('1740')"
>> castaging_test
>> do_parallel psql -p 5432  -c"select PushMarketSample('4400')"
>> castaging_test
>> do_parallel psql -p 5432  -c"select PushMarketSample('2160')"
>> castaging_test
>> do_parallel psql -p 5432  -c"select PushMarketSample('6680')"
>> castaging_test
>> <snip>
>> (do_parallel is simple wrapper to executing the command in parallel up
>> to NUM_FORKS).   This is on the same server and cluster as above.
>> This kind of suggests that either
>> A) there is some concurrent activity from another process that is
>> tripping the issue
>> or
>> B) there is something particular to the session invoking the function
>> that is participating in the problem.  As the application is
>> structured, a single threaded node.js app is issuing the query that is
>> high traffic and long lived.  It's still running in fact and I'm kind
>> of tempted to find some downtime to see if I can still reproduce via
>> the UI.
> Your production system's postgres backends probably have a lot more open
> files associated with them than the simple test case does.  Since Postgres
> likes to keep files open as long as possible and only closes them when you
> need to free up fds to open new files, it's possible that your production
> backends have almost all allowed fds used when you execute your pl/sh
> function.
> If that's the case, the sqsh process that's executed may not have enough fds
> to do what it wanted to do and because of busted error handling could end up
> writing to fds that were opened by Postgres and point to $PGDATA files.

Does that apply?  the mechanics are a sqsh function that basically does:
cat foo.sql  | sqsh <args>

pipe redirection opens a new process, right?


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