On Thu, Nov 28, 2019 at 4:10 PM Mahendra Singh <mahi6...@gmail.com> wrote: > > On Thu, 28 Nov 2019 at 13:32, Masahiko Sawada > <masahiko.saw...@2ndquadrant.com> wrote: >> >> On Wed, 27 Nov 2019 at 19:21, Mahendra Singh <mahi6...@gmail.com> wrote: >> > >> > >> > Thanks for the re-based patches. >> > >> > On the top of v35 patch, I can see one compilation warning. >> >> >> >> parallel.c: In function ‘LaunchParallelWorkers’: >> >> parallel.c:502:2: warning: ISO C90 forbids mixed declarations and code >> >> [-Wdeclaration-after-statement] >> >> int i; >> >> ^ >> > >> > >> > Above warning is due to one extra semicolon added at the end of >> > declaration line in v35-0003 patch. Please fix this in next version. >> > + int nworkers_to_launch = Min(nworkers, pcxt->nworkers);; >> >> Thanks. I will fix it in the next version patch. >> >> > >> > I will continue my testing on the top of v35 patch set and will post >> > results. > > > While reviewing v35 patch set and doing testing, I found that if we disable > leader participation, then we are launching 1 less parallel worker than total > number of indexes. (I am using max_parallel_workers = 20, > max_parallel_maintenance_workers = 20) > > For example: If table have 3 indexes and we gave 6 parallel vacuum > degree(leader participation is disabled), then I think, we should launch 3 > parallel workers but we are launching 2 workers due to below check. > + nworkers = lps->nindexes_parallel_bulkdel - 1; > + > + /* Cap by the worker we computed at the beginning of parallel lazy vacuum > */ > + nworkers = Min(nworkers, lps->pcxt->nworkers); > > Please let me know your thoughts for this. >
I think it is probably because this part of the code doesn't consider PARALLEL_VACUUM_DISABLE_LEADER_PARTICIPATION. I think if we want we can change it but I am slightly nervous about the code complexity this will bring but maybe that is fine. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
