On Sat, Jun 25, 2016 at 2:27 PM, Julien Rouhaud <julien.rouh...@dalibo.com> wrote: > On 25/06/2016 09:33, Amit Kapila wrote: >> On Wed, Jun 15, 2016 at 11:43 PM, Julien Rouhaud >> <julien.rouh...@dalibo.com> wrote: >>> >>> Attached v4 implements the design you suggested, I hope everything's ok. >>> >> >> Few review comments: >> > > Thanks for the review. > > > >> 4. >> + <varlistentry id="guc-max-parallel-workers" >> xreflabel="max_parallel_workers"> >> + <term><varname>max_parallel_workers</varname> (<type>integer</type>) >> + <indexterm> >> + <primary><varname>max_parallel_workers</> configuration >> parameter</primary> >> + </indexterm> >> + </term> >> + <listitem> >> + <para> >> + Sets the maximum number of workers that can be launched at the same >> + time for the whole server. This parameter allows the >> administrator to >> + reserve background worker slots for for third part dynamic >> background >> + workers. The default value is 4. Setting this value to 0 disables >> + parallel query execution. >> + </para> >> + </listitem> >> + </varlistentry> >> >> How about phrasing it as: >> Sets the maximum number of workers that the system can support for >> parallel queries. The default value is 4. Setting this value to 0 >> disables parallel query execution. >> > > It's better thanks. Should we document somewhere the link between this > parameter and custom dynamic background workers or is it pretty > self-explanatory? >
How about if add an additiona line like: Parallel workers are taken from the pool of processes established by guc-max-worker-processes. I think one might feel some duplication of text between this and what we have for max_parallel_workers_per_gather, but it seems genuine to me. @@ -370,6 +379,8 @@ ForgetBackgroundWorker(slist_mutable_iter *cur) Assert(rw->rw_shmem_slot < max_worker_processes); slot = &BackgroundWorkerData->slot[rw->rw_shmem_slot]; slot->in_use = false; + if (slot->parallel) + BackgroundWorkerData->parallel_terminate_count++; I think operations on parallel_terminate_count are not safe. ForgetBackgroundWorker() and RegisterDynamicBackgroundWorker() can try to read write at same time. It seems you need to use atomic operations to ensure safety. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
