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Implement new 'lightweight lock manager' that's intermediate between

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existing lock manager and spinlocks: it understands exclusive vs shared
lock but has few other fancy features.  Replace most uses of spinlocks
with lightweight locks.  All remaining uses of spinlocks have very short
lock hold times (a few dozen instructions), so tweak spinlock backoff
code to work efficiently given this assumption.  All per my proposal on
pghackers 26-Sep-01.
This commit is contained in:
Tom Lane
2001-09-29 04:02:27 +00:00
parent 818fb55ac4
commit 499abb0c0f
46 changed files with 1595 additions and 1355 deletions
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4
src/backend/commands/vacuumlazy.c
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@ -31,7 +31,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/vacuumlazy.c,v 1.7 2001/09/21 03:32:35 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/vacuumlazy.c,v 1.8 2001/09/29 04:02:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -53,7 +53,7 @@
* A page with less than PAGE_SPACE_THRESHOLD free space will be forgotten
* immediately, and not even passed to the free space map. Removing the
* uselessly small entries early saves cycles, and in particular reduces
* the amount of time we spend holding the FSM spinlock when we finally call
* the amount of time we spend holding the FSM lock when we finally call
* MultiRecordFreeSpace. Since the FSM will ignore pages below its own
* runtime threshold anyway, there's no point in making this really small.
* XXX Is it worth trying to measure average tuple size, and using that to