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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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27
src/backend/utils/hash/dynahash.c
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@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.53 2004/08/29 05:06:50 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.54 2004/09/28 20:46:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -63,7 +63,7 @@
*/
static void *DynaHashAlloc(Size size);
static HASHSEGMENT seg_alloc(HTAB *hashp);
static bool element_alloc(HTAB *hashp);
static bool element_alloc(HTAB *hashp, int nelem);
static bool dir_realloc(HTAB *hashp);
static bool expand_table(HTAB *hashp);
static bool hdefault(HTAB *hashp);
@@ -228,11 +228,26 @@ hash_create(const char *tabname, long nelem, HASHCTL *info, int flags)
CurrentDynaHashCxt = hashp->hcxt;
}
/* Build the hash directory structure */
if (!init_htab(hashp, nelem))
{
hash_destroy(hashp);
return NULL;
}
/*
* For a shared hash table, preallocate the requested number of elements.
* This reduces problems with run-time out-of-shared-memory conditions.
*/
if (flags & HASH_SHARED_MEM)
{
if (!element_alloc(hashp, (int) nelem))
{
hash_destroy(hashp);
return NULL;
}
}
return hashp;
}
@@ -631,7 +646,7 @@ hash_search(HTAB *hashp,
if (currBucket == NULL)
{
/* no free elements. allocate another chunk of buckets */
if (!element_alloc(hashp))
if (!element_alloc(hashp, HASHELEMENT_ALLOC_INCR))
return NULL; /* out of memory */
currBucket = hctl->freeList;
Assert(currBucket != NULL);
@@ -898,7 +913,7 @@ seg_alloc(HTAB *hashp)
* allocate some new elements and link them into the free list
*/
static bool
element_alloc(HTAB *hashp)
element_alloc(HTAB *hashp, int nelem)
{
HASHHDR *hctl = hashp->hctl;
Size elementSize;
@@ -910,13 +925,13 @@ element_alloc(HTAB *hashp)
CurrentDynaHashCxt = hashp->hcxt;
tmpElement = (HASHELEMENT *)
hashp->alloc(HASHELEMENT_ALLOC_INCR * elementSize);
hashp->alloc(nelem * elementSize);
if (!tmpElement)
return false;
/* link all the new entries into the freelist */
for (i = 0; i < HASHELEMENT_ALLOC_INCR; i++)
for (i = 0; i < nelem; i++)
{
tmpElement->link = hctl->freeList;
hctl->freeList = tmpElement;