回复: 回复: [PATCH] BUG FIX: Core dump could happen when VACUUM FULL in standalone mode

I think you are right after reading code in compute_parallel_vacuum_workers() :)

________________________________
发件人: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
发送时间: 2020年12月1日 2:54
收件人: Yulin PEI <ypeiae(at)connect(dot)ust(dot)hk>
抄送: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>; pgsql-hackers(at)lists(dot)postgresql(dot)org <pgsql-hackers(at)lists(dot)postgresql(dot)org>
主题: Re: 回复: [PATCH] BUG FIX: Core dump could happen when VACUUM FULL in standalone mode

Yulin PEI <ypeiae(at)connect(dot)ust(dot)hk> writes:
> Yes, I agree because (IsNormalProcessingMode() ) means that current process is not in bootstrap mode and postmaster process will not build index.
> So my new modified patch is attached.

This is a good catch, but the proposed fix still seems pretty random
and unlike how it's done elsewhere. It seems to me that since
index_build() is relying on plan_create_index_workers() to assess
parallel safety, that's where to check IsUnderPostmaster. Moreover,
the existing code in compute_parallel_vacuum_workers (which gets
this right) associates the IsUnderPostmaster check with the initial
check on max_parallel_maintenance_workers. So I think that the
right fix is to adopt the compute_parallel_vacuum_workers coding
in plan_create_index_workers, and thereby create a model for future
uses of max_parallel_maintenance_workers to follow.

regards, tom lane