Integrate dynahash patch by Alexander Alexeev. This fix lock contension for shared memory

vbwagner · vbwagner · commit 90e649a7afac · 2015-12-31T09:52:30.000+03:00
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -495,7 +495,7 @@ pgss_shmem_startup(void)
 	info.hash = pgss_hash_fn;
 	info.match = pgss_match_fn;
 	pgss_hash = ShmemInitHash("pg_stat_statements hash",
-							  pgss_max, pgss_max,
+							  pgss_max,
 							  &info,
 							  HASH_ELEM | HASH_FUNCTION | HASH_COMPARE);
 
diff --git a/doc/src/sgml/release-pro-9.5.sgml b/doc/src/sgml/release-pro-9.5.sgml
@@ -103,11 +103,17 @@
     and queries which use large number of resoures
 -->
     <para>Resource owner optimisation for complicated queries: now
-
     resource lists has constant access time, which improves performance
     for heavily partitioned tables and queries which use hundreds of
     tables.
     </para>
+    </listitem>
+    <listitem>
+    <para>
+    Fix lock contention for HASHHDR.mutex. (Alexander Alexeev). This
+    prevents Postgres from waiting for lock up to several milliseconds
+    when modifying state, shared between processes.
+    </para>
     </listitem>
      </itemizedlist>
     </listitem>
diff --git a/src/backend/storage/buffer/buf_table.c b/src/backend/storage/buffer/buf_table.c
@@ -62,7 +62,7 @@ InitBufTable(int size)
 	info.num_partitions = NUM_BUFFER_PARTITIONS;
 
 	SharedBufHash = ShmemInitHash("Shared Buffer Lookup Table",
-								  size, size,
+								  size,
 								  &info,
 								  HASH_ELEM | HASH_BLOBS | HASH_PARTITION);
 }
diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c
@@ -240,7 +240,7 @@ InitShmemIndex(void)
 	hash_flags = HASH_ELEM;
 
 	ShmemIndex = ShmemInitHash("ShmemIndex",
-							   SHMEM_INDEX_SIZE, SHMEM_INDEX_SIZE,
+							   SHMEM_INDEX_SIZE,
 							   &info, hash_flags);
 }
 
@@ -258,17 +258,12 @@ InitShmemIndex(void)
  * 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.
- *
  * Note: before Postgres 9.0, this function returned NULL for some failure
  * cases.  Now, it always throws error instead, so callers need not check
  * for NULL.
  */
 HTAB *
 ShmemInitHash(const char *name, /* table string name for shmem index */
-			  long init_size,	/* initial table size */
 			  long max_size,	/* max size of the table */
 			  HASHCTL *infoP,	/* info about key and bucket size */
 			  int hash_flags)	/* info about infoP */
@@ -302,7 +297,7 @@ ShmemInitHash(const char *name, /* table string name for shmem index */
 	/* Pass location of hashtable header to hash_create */
 	infoP->hctl = (HASHHDR *) location;
 
-	return hash_create(name, init_size, infoP, hash_flags);
+	return hash_create(name, max_size, infoP, hash_flags);
 }
 
 /*
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
@@ -373,16 +373,14 @@ void
 InitLocks(void)
 {
 	HASHCTL		info;
-	long		init_table_size,
-				max_table_size;
+	long		max_table_size;
 	bool		found;
 
 	/*
 	 * Compute init/max size to request for lock hashtables.  Note these
 	 * calculations must agree with LockShmemSize!
 	 */
 	max_table_size = NLOCKENTS();
-	init_table_size = max_table_size / 2;
 
 	/*
 	 * Allocate hash table for LOCK structs.  This stores per-locked-object
@@ -394,14 +392,12 @@ InitLocks(void)
 	info.num_partitions = NUM_LOCK_PARTITIONS;
 
 	LockMethodLockHash = ShmemInitHash("LOCK hash",
-									   init_table_size,
 									   max_table_size,
 									   &info,
 									HASH_ELEM | HASH_BLOBS | HASH_PARTITION);
 
 	/* Assume an average of 2 holders per lock */
 	max_table_size *= 2;
-	init_table_size *= 2;
 
 	/*
 	 * Allocate hash table for PROCLOCK structs.  This stores
@@ -413,7 +409,6 @@ InitLocks(void)
 	info.num_partitions = NUM_LOCK_PARTITIONS;
 
 	LockMethodProcLockHash = ShmemInitHash("PROCLOCK hash",
-										   init_table_size,
 										   max_table_size,
 										   &info,
 								 HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
@@ -1115,7 +1115,6 @@ InitPredicateLocks(void)
 	info.num_partitions = NUM_PREDICATELOCK_PARTITIONS;
 
 	PredicateLockTargetHash = ShmemInitHash("PREDICATELOCKTARGET hash",
-											max_table_size,
 											max_table_size,
 											&info,
 											HASH_ELEM | HASH_BLOBS |
@@ -1143,7 +1142,6 @@ InitPredicateLocks(void)
 	info.num_partitions = NUM_PREDICATELOCK_PARTITIONS;
 
 	PredicateLockHash = ShmemInitHash("PREDICATELOCK hash",
-									  max_table_size,
 									  max_table_size,
 									  &info,
 									  HASH_ELEM | HASH_FUNCTION |
@@ -1224,7 +1222,6 @@ InitPredicateLocks(void)
 	info.entrysize = sizeof(SERIALIZABLEXID);
 
 	SerializableXidHash = ShmemInitHash("SERIALIZABLEXID hash",
-										max_table_size,
 										max_table_size,
 										&info,
 										HASH_ELEM | HASH_BLOBS |
diff --git a/src/backend/utils/hash/dynahash.c b/src/backend/utils/hash/dynahash.c
diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h
diff --git a/src/include/storage/shmem.h b/src/include/storage/shmem.h

Original file line number	Diff line number	Diff line change
`@@ -62,7 +62,7 @@ InitBufTable(int size)`
`62`	`62`	`info.num_partitions = NUM_BUFFER_PARTITIONS;`
`63`	`63`
`64`	`64`	`SharedBufHash = ShmemInitHash("Shared Buffer Lookup Table",`
`65`		`- size, size,`
	`65`	`+ size,`
`66`	`66`	`&info,`
`67`	`67`	`HASH_ELEM \| HASH_BLOBS \| HASH_PARTITION);`
`68`	`68`	`}`