Horton

Re: Speed up Clog Access by increasing CLOG buffers

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Michael Paquier <michael.paquier@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Jim Nasby <Jim.Nasby@bluetreble.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-04-07T17:47:38Z
Lists: pgsql-hackers 
On Thu, Mar 9, 2017 at 5:49 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> However, I just realized that in
> both this case and in the case of group XID clearing, we weren't
> advertising a wait event for the PGSemaphoreLock calls that are part
> of the group locking machinery.  I think we should fix that, because a
> quick test shows that can happen fairly often -- not, I think, as
> often as we would have seen LWLock waits without these patches, but
> often enough that you'll want to know.  Patch attached.

I've pushed the portion of this that relates to ProcArrayLock.  (I
know this hasn't been discussed much, but there doesn't really seem to
be any reason for anybody to object, and looking at just the
LWLock/ProcArrayLock wait events gives a highly misleading answer.)

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Use group updates when setting transaction status in clog.

  2. Improve 64bit atomics support.

  3. Add ProcArrayGroupUpdate wait event.

  4. Make the different Unix-y semaphore implementations ABI-compatible.

  5. Fix broken ALTER INDEX documentation

  6. Code and docs review for commit 3187d6de0e5a9e805b27c48437897e8c39071d45.

  7. Partition the freelist for shared dynahash tables.

  8. Correct StartupSUBTRANS for page wraparound

  9. Make idle backends exit if the postmaster dies.

  10. contrib/sslinfo: add ssl_extension_info SRF

  11. Reduce ProcArrayLock contention by removing backends in batches.

  12. Fix `make installcheck` for serializable transactions.

  13. Lockless StrategyGetBuffer clock sweep hot path.

  14. Reduce sinval synchronization overhead.