On Wed, Apr 5, 2017 at 10:09 AM, Kuntal Ghosh
<kuntalghosh.2007@gmail.com> wrote:
>> Did you intend to attach that patch to this email?
>>
> Actually, I'm confused how we should ensure (register_count >
> terminate_count) invariant. I think there can be a system crash what
> Tomas has suggested up in the thread.
>
> Assert(parallel_register_count - parallel_terminate_count <=
> max_parallel_workers);
> Backend 1 > SET max_parallel_worker = 8;
> Backend 1 > Execute a long running parallel query q1 with number of
> parallel worker spawned is say, 4.
At this point, parallel_register_count should be equal to
parallel_terminate_count. 4 workers were started, and 4 have
terminated.
> Backend 2> SET max_parallel_worker = 3;
> Backend 2 > Try to execute any parallel query q2 with number of
> parallel worker spawned > 0.
Now here parallel_register_count should get bumped up to 4+(# of
workers now launched) at the beginning and then
parallel_terminate_count at the end. No problem.
What's going wrong, here?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
