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Arrange to preallocate all required space for the buffer and FSM hash
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
parent
d9b68c8061
commit
3a246cc285
@ -8,7 +8,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/freespace/freespace.c,v 1.34 2004/08/29 05:06:47 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/storage/freespace/freespace.c,v 1.35 2004/09/28 20:46:27 tgl Exp $
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*
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*
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* NOTES:
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@ -283,8 +283,8 @@ InitFreeSpaceMap(void)
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info.hash = tag_hash;
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FreeSpaceMapRelHash = ShmemInitHash("Free Space Map Hash",
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MaxFSMRelations / 10,
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MaxFSMRelations,
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MaxFSMRelations + 1,
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MaxFSMRelations + 1,
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&info,
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(HASH_ELEM | HASH_FUNCTION));
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/ipc/shmem.c,v 1.80 2004/08/29 05:06:48 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/storage/ipc/shmem.c,v 1.81 2004/09/28 20:46:29 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -262,8 +262,17 @@ InitShmemIndex(void)
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* shared memory hash table.
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*
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* We assume caller is doing some kind of synchronization
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* so that two people dont try to create/initialize the
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* so that two people don't try to create/initialize the
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* table at once.
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*
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* max_size is the estimated maximum number of hashtable entries. This is
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* not a hard limit, but the access efficiency will degrade if it is
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* exceeded substantially (since it's used to compute directory size and
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* the hash table buckets will get overfull).
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*
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* init_size is the number of hashtable entries to preallocate. For a table
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* whose maximum size is certain, this should be equal to max_size; that
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* ensures that no run-time out-of-shared-memory failures can occur.
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*/
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HTAB *
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ShmemInitHash(const char *name, /* table string name for shmem index */
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.140 2004/09/12 18:30:50 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.141 2004/09/28 20:46:32 tgl Exp $
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*
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* NOTES
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* Outside modules can create a lock table and acquire/release
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@ -241,7 +241,7 @@ LockMethodTableInit(const char *tabName,
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/* Compute init/max size to request for lock hashtables */
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max_table_size = NLOCKENTS(maxBackends);
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init_table_size = max_table_size / 10;
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init_table_size = max_table_size / 2;
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/* Allocate a string for the shmem index table lookups. */
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/* This is just temp space in this routine, so palloc is OK. */
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@ -9,7 +9,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.53 2004/08/29 05:06:50 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.54 2004/09/28 20:46:34 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -63,7 +63,7 @@
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*/
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static void *DynaHashAlloc(Size size);
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static HASHSEGMENT seg_alloc(HTAB *hashp);
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static bool element_alloc(HTAB *hashp);
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static bool element_alloc(HTAB *hashp, int nelem);
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static bool dir_realloc(HTAB *hashp);
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static bool expand_table(HTAB *hashp);
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static bool hdefault(HTAB *hashp);
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@ -228,11 +228,26 @@ hash_create(const char *tabname, long nelem, HASHCTL *info, int flags)
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CurrentDynaHashCxt = hashp->hcxt;
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}
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/* Build the hash directory structure */
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if (!init_htab(hashp, nelem))
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{
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hash_destroy(hashp);
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return NULL;
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}
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/*
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* For a shared hash table, preallocate the requested number of elements.
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* This reduces problems with run-time out-of-shared-memory conditions.
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*/
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if (flags & HASH_SHARED_MEM)
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{
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if (!element_alloc(hashp, (int) nelem))
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{
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hash_destroy(hashp);
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return NULL;
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}
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}
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return hashp;
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}
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@ -631,7 +646,7 @@ hash_search(HTAB *hashp,
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if (currBucket == NULL)
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{
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/* no free elements. allocate another chunk of buckets */
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if (!element_alloc(hashp))
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if (!element_alloc(hashp, HASHELEMENT_ALLOC_INCR))
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return NULL; /* out of memory */
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currBucket = hctl->freeList;
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Assert(currBucket != NULL);
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@ -898,7 +913,7 @@ seg_alloc(HTAB *hashp)
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* allocate some new elements and link them into the free list
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*/
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static bool
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element_alloc(HTAB *hashp)
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element_alloc(HTAB *hashp, int nelem)
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{
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HASHHDR *hctl = hashp->hctl;
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Size elementSize;
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@ -910,13 +925,13 @@ element_alloc(HTAB *hashp)
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CurrentDynaHashCxt = hashp->hcxt;
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tmpElement = (HASHELEMENT *)
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hashp->alloc(HASHELEMENT_ALLOC_INCR * elementSize);
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hashp->alloc(nelem * elementSize);
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if (!tmpElement)
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return false;
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/* link all the new entries into the freelist */
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for (i = 0; i < HASHELEMENT_ALLOC_INCR; i++)
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for (i = 0; i < nelem; i++)
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{
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tmpElement->link = hctl->freeList;
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hctl->freeList = tmpElement;
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/storage/shmem.h,v 1.42 2004/08/29 04:13:10 momjian Exp $
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* $PostgreSQL: pgsql/src/include/storage/shmem.h,v 1.43 2004/09/28 20:46:35 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -73,8 +73,8 @@ extern void *ShmemInitStruct(const char *name, Size size, bool *foundPtr);
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/* size constants for the shmem index table */
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/* max size of data structure string name */
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#define SHMEM_INDEX_KEYSIZE (48)
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/* maximum size of the shmem index table */
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#define SHMEM_INDEX_SIZE (100)
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/* max size of the shmem index table (not a hard limit) */
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#define SHMEM_INDEX_SIZE (32)
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/* this is a hash bucket in the shmem index table */
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typedef struct
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.32 2004/08/29 05:06:59 momjian Exp $
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* $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.33 2004/09/28 20:46:37 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -135,7 +135,7 @@ typedef struct HASHCTL
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#define HASH_FFACTOR 0x008 /* Set fill factor */
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#define HASH_FUNCTION 0x010 /* Set user defined hash function */
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#define HASH_ELEM 0x020 /* Set key/entry size */
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#define HASH_SHARED_MEM 0x040 /* Set shared mem const */
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#define HASH_SHARED_MEM 0x040 /* Hashtable is in shared memory */
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#define HASH_ATTACH 0x080 /* Do not initialize hctl */
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#define HASH_ALLOC 0x100 /* Set memory allocator */
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#define HASH_CONTEXT 0x200 /* Set explicit memory context */
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