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Arrange to preallocate all required space for the buffer and FSM hash

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tables in shared memory.  This ensures that overflow of the lock table
creates no long-lasting problems.  Per discussion with Merlin Moncure.
This commit is contained in:
Tom Lane
2004-09-28 20:46:37 +00:00
parent d9b68c8061
commit 3a246cc285
6 changed files with 42 additions and 18 deletions
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6
src/backend/storage/freespace/freespace.c
View File

@@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/freespace/freespace.c,v 1.34 2004/08/29 05:06:47 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/freespace/freespace.c,v 1.35 2004/09/28 20:46:27 tgl Exp $
*
*
* NOTES:
@@ -283,8 +283,8 @@ InitFreeSpaceMap(void)
info.hash = tag_hash;
FreeSpaceMapRelHash = ShmemInitHash("Free Space Map Hash",
MaxFSMRelations / 10,
MaxFSMRelations,
MaxFSMRelations + 1,
MaxFSMRelations + 1,
&info,
(HASH_ELEM | HASH_FUNCTION));

13
src/backend/storage/ipc/shmem.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/ipc/shmem.c,v 1.80 2004/08/29 05:06:48 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/ipc/shmem.c,v 1.81 2004/09/28 20:46:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -262,8 +262,17 @@ InitShmemIndex(void)
* shared memory hash table.
*
* We assume caller is doing some kind of synchronization
* so that two people dont try to create/initialize the
* so that two people don't try to create/initialize the
* table at once.
*
* max_size is the estimated maximum number of hashtable entries. This is
* not a hard limit, but the access efficiency will degrade if it is
* exceeded substantially (since it's used to compute directory size and
* the hash table buckets will get overfull).
*
* init_size is the number of hashtable entries to preallocate. For a table
* whose maximum size is certain, this should be equal to max_size; that
* ensures that no run-time out-of-shared-memory failures can occur.
*/
HTAB *
ShmemInitHash(const char *name, /* table string name for shmem index */

4
src/backend/storage/lmgr/lock.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.140 2004/09/12 18:30:50 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.141 2004/09/28 20:46:32 tgl Exp $
*
* NOTES
* Outside modules can create a lock table and acquire/release
@@ -241,7 +241,7 @@ LockMethodTableInit(const char *tabName,
/* Compute init/max size to request for lock hashtables */
max_table_size = NLOCKENTS(maxBackends);
init_table_size = max_table_size / 10;
init_table_size = max_table_size / 2;
/* Allocate a string for the shmem index table lookups. */
/* This is just temp space in this routine, so palloc is OK. */