Horton

Re: Speed up Clog Access by increasing CLOG buffers

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Michael Paquier <michael.paquier@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: 2017-03-10T22:19:17Z
Lists: pgsql-hackers 
Robert Haas wrote:

> The smoking gun was in 009_twophase_slave.log:
> 
> TRAP: FailedAssertion("!(nsubxids == MyPgXact->nxids)", File:
> "clog.c", Line: 288)
> 
> ...and then the node shuts down, which is why this hangs forever.
> (Also... what's up with it hanging forever instead of timing out or
> failing or something?)

This bit my while messing with 2PC tests recently.  I think it'd be
worth doing something about this, such as causing the test to die if we
request a server to (re)start and it doesn't start or it immediately
crashes.  This doesn't solve the problem of a server crashing at a point
not immediately after start, though.

(It'd be very annoying to have to sprinkle the Perl test code with
"assert $server->islive", but perhaps we can add assertions of some kind
in PostgresNode itself).

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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.