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Replace buffer I/O locks with condition variables.

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1.  Backends waiting for buffer I/O are now interruptible.

2.  If something goes wrong in a backend that is currently performing
I/O, waiting backends no longer wake up until that backend reaches
AbortBufferIO() and broadcasts on the CV.  Previously, any waiters would
wake up (because the I/O lock was automatically released) and then
busy-loop until AbortBufferIO() cleared BM_IO_IN_PROGRESS.

3.  LWLockMinimallyPadded is removed, as it would now be unused.

Author: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (earlier version, 2016)
Discussion: https://postgr.es/m/CA%2BhUKGJ8nBFrjLuCTuqKN0pd2PQOwj9b_jnsiGFFMDvUxahj_A%40mail.gmail.com
Discussion: https://postgr.es/m/CA+Tgmoaj2aPti0yho7FeEf2qt-JgQPRWb0gci_o1Hfr=C56Xng@mail.gmail.com
This commit is contained in:
Thomas Munro
2021-03-11 10:05:58 +13:00
parent c3ffe34863
commit d87251048a
11 changed files with 61 additions and 116 deletions
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11
src/include/storage/condition_variable.h
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@@ -31,6 +31,17 @@ typedef struct
proclist_head wakeup; /* list of wake-able processes */
} ConditionVariable;
/*
* Pad a condition variable to a power-of-two size so that an array of
* condition variables does not cross a cache line boundary.
*/
#define CV_MINIMAL_SIZE (sizeof(ConditionVariable) <= 16 ? 16 : 32)
typedef union ConditionVariableMinimallyPadded
{
ConditionVariable cv;
char pad[CV_MINIMAL_SIZE];
} ConditionVariableMinimallyPadded;
/* Initialize a condition variable. */
extern void ConditionVariableInit(ConditionVariable *cv);