On Mon, Mar 4, 2019 at 3:43 PM Dave Page <dp...@pgadmin.org> wrote: > Hi > > On Mon, Mar 4, 2019 at 5:43 AM Khushboo Vashi < > khushboo.va...@enterprisedb.com> wrote: > >> >> >> On Fri, Mar 1, 2019 at 10:01 PM Dave Page <dp...@pgadmin.org> wrote: >> >>> In investigating #3656 I found the initial problem to be that when >>> running in a container, Gunicorn will kill the worker process if a thread >>> doesn't respond for 30 seconds by default. I fixed that by making the >>> timeout match the application session timeout, but it revealed another >>> issue. >>> >>> Given the function below (from the ticket), if you open the query tool >>> and run: >>> >>> SELECT 1; SELECT fails_after(30); >>> >>> the async query actually blocks for 30 seconds in the cur.execute() call >>> in execute_async() in connection.py (line 968). This causes the entire app >>> to hang (watch the dashboard requests pile up in pending state in the >>> network tab of the browser dev tools). >>> >>> If you run just the second SELECT, it works as expected, as does running >>> something like: >>> >>> SELECT 1; SELECT pg_sleep(30); >>> >>> Anyone have any idea what's going on? >>> >> >> Connection.poll() blocking the call here. ( connection.py - _wait_timeout >> function line #1378 state = conn.poll() ) >> In the asynchronous connection, after executing the query, the >> conn.poll() is being called to fetch the connection status. >> It gives the status accordingly but in this case, it is blocking and not >> giving the status. >> > > If I put a breakpoint on the _wait_timeout call (line 969 in > execute_async), it hits it *after* the 30 seconds has passed (during which > time all other queries for cancel or dashboards and status etc don't get > processed). > > Put the breakpoint in the _wait_timeout function itself. The line no 1378 (state = conn.poll()) is blocking the execution 30 seconds.
> If I walk down the call stack, it returns from the _cursor.execute call in > cursor.py and then hangs right before it goes into _wait_timeout. > > -- > Dave Page > Blog: http://pgsnake.blogspot.com > Twitter: @pgsnake > > EnterpriseDB UK: http://www.enterprisedb.com > The Enterprise PostgreSQL Company >
