Horton

Re: remove spurious CREATE INDEX CONCURRENTLY wait

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, James Coleman <jtc331@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2020-11-10T01:32:13Z
Lists: pgsql-hackers 
Michael Paquier <michael@paquier.xyz> writes:
>> +		LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
>> +		MyProc->vacuumFlags |= PROC_IN_SAFE_IC;
>> +		ProcGlobal->vacuumFlags[MyProc->pgxactoff] = MyProc->vacuumFlags;
>> +		LWLockRelease(ProcArrayLock);

> I can't help noticing that you are repeating the same code pattern
> eight times.  I think that this should be in its own routine, and that
> we had better document that this should be called just after starting
> a transaction, with an assertion enforcing that.

Do we really need exclusive lock on the ProcArray to make this flag
change?  That seems pretty bad from a concurrency standpoint.

			regards, tom lane

Commits

  1. Restore lock level to set vacuum flags

  2. Restore lock level to update statusFlags

  3. Avoid spurious waits in concurrent indexing

  4. Centralize logic for skipping useless ereport/elog calls.

  5. Don't hold ProcArrayLock longer than needed in rare cases

  6. Relax lock level for setting PGPROC->statusFlags

  7. Rename PGPROC->vacuumFlags to statusFlags

  8. snapshot scalability: Move PGXACT->vacuumFlags to ProcGlobal->vacuumFlags.

  9. Allow an autovacuum worker to be interrupted automatically when it is found