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Split the shared-memory array of PGPROC pointers out of the sinval

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communication structure, and make it its own module with its own lock.
This should reduce contention at least a little, and it definitely makes
the code seem cleaner.  Per my recent proposal.
This commit is contained in:
Tom Lane
2005-05-19 21:35:48 +00:00
parent 6910032a56
commit ee3b71f6bc
30 changed files with 923 additions and 860 deletions
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12
src/backend/access/transam/xlog.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.191 2005/05/10 22:27:29 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.192 2005/05/19 21:35:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -38,7 +38,7 @@
#include "storage/lwlock.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/sinval.h"
#include "storage/procarray.h"
#include "storage/spin.h"
#include "utils/builtins.h"
#include "utils/guc.h"
@ -776,7 +776,7 @@ begin:;
if (MyLastRecPtr.xrecoff == 0 && !no_tran)
{
/*
* We do not acquire SInvalLock here because of possible deadlock.
* We do not acquire ProcArrayLock here because of possible deadlock.
* Anyone who wants to inspect other procs' logRec must acquire
* WALInsertLock, instead. A better solution would be a per-PROC
* spinlock, but no time for that before 7.2 --- tgl 12/19/01.
@ -4887,11 +4887,11 @@ CreateCheckPoint(bool shutdown, bool force)
* commits after REDO point).
*
* XXX temporarily ifdef'd out to avoid three-way deadlock condition:
* GetUndoRecPtr needs to grab SInvalLock to ensure that it is looking
* at a stable set of proc records, but grabbing SInvalLock while
* GetUndoRecPtr needs to grab ProcArrayLock to ensure that it is looking
* at a stable set of proc records, but grabbing ProcArrayLock while
* holding WALInsertLock is no good. GetNewTransactionId may cause a
* WAL record to be written while holding XidGenLock, and
* GetSnapshotData needs to get XidGenLock while holding SInvalLock,
* GetSnapshotData needs to get XidGenLock while holding ProcArrayLock,
* so there's a risk of deadlock. Need to find a better solution. See
* pgsql-hackers discussion of 17-Dec-01.
*