From 7c797e7194d969f974abf579cacf30ffdccdbb95 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Mon, 11 Apr 2011 13:43:31 +0300
Subject: [PATCH] Fix the size of predicate lock manager's shared memory hash
tables at creation.
This way they don't compete with the regular lock manager for the slack shared
memory, making the behavior more predictable.
---
src/backend/storage/lmgr/predicate.c | 22 +++++++++-------------
src/backend/utils/hash/dynahash.c | 6 ++++++
src/include/utils/hsearch.h | 1 +
3 files changed, 16 insertions(+), 13 deletions(-)
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index 72385c2f3e..eceb384e58 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -970,17 +970,15 @@ InitPredicateLocks(void)
{
HASHCTL info;
int hash_flags;
- long init_table_size,
- max_table_size;
+ long max_table_size;
Size requestSize;
bool found;
/*
- * Compute init/max size to request for predicate lock target hashtable.
+ * Compute size of predicate lock target hashtable.
* Note these calculations must agree with PredicateLockShmemSize!
*/
max_table_size = NPREDICATELOCKTARGETENTS();
- init_table_size = max_table_size / 2;
/*
* Allocate hash table for PREDICATELOCKTARGET structs. This stores
@@ -991,17 +989,16 @@ InitPredicateLocks(void)
info.entrysize = sizeof(PREDICATELOCKTARGET);
info.hash = tag_hash;
info.num_partitions = NUM_PREDICATELOCK_PARTITIONS;
- hash_flags = (HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
+ hash_flags = (HASH_ELEM | HASH_FUNCTION | HASH_PARTITION | HASH_FIXED_SIZE);
PredicateLockTargetHash = ShmemInitHash("PREDICATELOCKTARGET hash",
- init_table_size,
+ max_table_size,
max_table_size,
&info,
hash_flags);
/* Assume an average of 2 xacts per target */
max_table_size *= 2;
- init_table_size *= 2;
/*
* Reserve an entry in the hash table; we use it to make sure there's
@@ -1022,18 +1019,17 @@ InitPredicateLocks(void)
info.entrysize = sizeof(PREDICATELOCK);
info.hash = predicatelock_hash;
info.num_partitions = NUM_PREDICATELOCK_PARTITIONS;
- hash_flags = (HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
+ hash_flags = (HASH_ELEM | HASH_FUNCTION | HASH_PARTITION | HASH_FIXED_SIZE);
PredicateLockHash = ShmemInitHash("PREDICATELOCK hash",
- init_table_size,
+ max_table_size,
max_table_size,
&info,
hash_flags);
/*
- * Compute init/max size to request for serializable transaction
- * hashtable. Note these calculations must agree with
- * PredicateLockShmemSize!
+ * Compute size for serializable transaction hashtable.
+ * Note these calculations must agree with PredicateLockShmemSize!
*/
max_table_size = (MaxBackends + max_prepared_xacts);
@@ -1104,7 +1100,7 @@ InitPredicateLocks(void)
info.keysize = sizeof(SERIALIZABLEXIDTAG);
info.entrysize = sizeof(SERIALIZABLEXID);
info.hash = tag_hash;
- hash_flags = (HASH_ELEM | HASH_FUNCTION);
+ hash_flags = (HASH_ELEM | HASH_FUNCTION | HASH_FIXED_SIZE);
SerializableXidHash = ShmemInitHash("SERIALIZABLEXID hash",
max_table_size,
diff --git a/src/backend/utils/hash/dynahash.c b/src/backend/utils/hash/dynahash.c
index f718785ee4..d9027291ee 100644
--- a/src/backend/utils/hash/dynahash.c
+++ b/src/backend/utils/hash/dynahash.c
@@ -160,6 +160,7 @@ struct HTAB
MemoryContext hcxt; /* memory context if default allocator used */
char *tabname; /* table name (for error messages) */
bool isshared; /* true if table is in shared memory */
+ bool isfixed; /* if true, don't enlarge */
/* freezing a shared table isn't allowed, so we can keep state here */
bool frozen; /* true = no more inserts allowed */
@@ -435,6 +436,8 @@ hash_create(const char *tabname, long nelem, HASHCTL *info, int flags)
errmsg("out of memory")));
}
+ if (flags & HASH_FIXED_SIZE)
+ hashp->isfixed = true;
return hashp;
}
@@ -1334,6 +1337,9 @@ element_alloc(HTAB *hashp, int nelem)
HASHELEMENT *prevElement;
int i;
+ if (hashp->isfixed)
+ return false;
+
/* Each element has a HASHELEMENT header plus user data. */
elementSize = MAXALIGN(sizeof(HASHELEMENT)) + MAXALIGN(hctlv->entrysize);
diff --git a/src/include/utils/hsearch.h b/src/include/utils/hsearch.h
index bca34d23e2..ce54c0a21b 100644
--- a/src/include/utils/hsearch.h
+++ b/src/include/utils/hsearch.h
@@ -92,6 +92,7 @@ typedef struct HASHCTL
#define HASH_CONTEXT 0x200 /* Set memory allocation context */
#define HASH_COMPARE 0x400 /* Set user defined comparison function */
#define HASH_KEYCOPY 0x800 /* Set user defined key-copying function */
+#define HASH_FIXED_SIZE 0x1000 /* Initial size is a hard limit */
/* max_dsize value to indicate expansible directory */