Merge lp:~akopytov/percona-server/bug1131187 into lp:percona-server/5.5

[Alexey Kopytov]

  Bug #1131187: Remove malloc() from read_view_create_low()

  Avoid malloc() thrashing in read_view_create_low() by using a
  pre-allocated view array.

http://jenkins.percona.com/view/PS%205.5/job/percona-server-5.5-param/682/

[Stewart Smith (stewart)]

review: Approve

=== modified file 'Percona-Server/storage/innobase/include/read0read.h'
--- Percona-Server/storage/innobase/include/read0read.h	2012-04-18 23:24:45 +0000
+++ Percona-Server/storage/innobase/include/read0read.h	2013-03-15 09:57:21 +0000
@@ -44,8 +44,8 @@
 /*===============*/
 	trx_id_t	cr_trx_id,	/*!< in: trx_id of creating
 					transaction, or 0 used in purge */
-	mem_heap_t*	heap);		/*!< in: memory heap from which
-					allocated */
+	read_view_t*	view);		/*!< in: pre-allocated view array or
+					NULL if a new one needs to be created */
 /*********************************************************************//**
 Makes a copy of the oldest existing read view, or opens a new. The view
 must be closed with ..._close.
@@ -56,8 +56,8 @@
 /*==============================*/
 	trx_id_t	cr_trx_id,	/*!< in: trx_id of creating
 					transaction, or 0 used in purge */
-	mem_heap_t*	heap);		/*!< in: memory heap from which
-					allocated */
+	read_view_t*	view);		/*!< in: pre-allocated view array or
+					NULL if a new one needs to be created */
 /*********************************************************************//**
 Closes a read view. */
 UNIV_INTERN
@@ -66,6 +66,13 @@
 /*============*/
 	read_view_t*	view);	/*!< in: read view */
 /*********************************************************************//**
+Frees memory allocated by a read view. */
+UNIV_INTERN
+void
+read_view_free(
+/*===========*/
+	read_view_t*	view);	/*< in: read view */
+/*********************************************************************//**
 Closes a consistent read view for MySQL. This function is called at an SQL
 statement end if the trx isolation level is <= TRX_ISO_READ_COMMITTED. */
 UNIV_INTERN
@@ -145,6 +152,9 @@
 				this is the "low water mark". */
 	ulint		n_trx_ids;
 				/*!< Number of cells in the trx_ids array */
+	ulint		max_trx_ids;
+				/*!< Maximum number of cells in the trx_ids
+				array */
 	trx_id_t*	trx_ids;/*!< Additional trx ids which the read should
 				not see: typically, these are the active
 				transactions at the time when the read is
 
=== modified file 'Percona-Server/storage/innobase/include/trx0purge.h'
--- Percona-Server/storage/innobase/include/trx0purge.h	2013-02-18 04:48:10 +0000
+++ Percona-Server/storage/innobase/include/trx0purge.h	2013-03-15 09:57:21 +0000
@@ -143,6 +143,7 @@
 					obtaining an s-latch here. */
 	read_view_t*	view;		/*!< The purge will not remove undo logs
 					which are >= this view (purge view) */
+	read_view_t*	prebuilt_view;	/*!< Pre-built view array */
 	ulonglong	n_pages_handled;/*!< Approximate number of undo log
 					pages processed in purge */
 	ulonglong	handle_limit;	/*!< Target of how many pages to get
 
=== modified file 'Percona-Server/storage/innobase/include/trx0trx.h'
--- Percona-Server/storage/innobase/include/trx0trx.h	2012-05-10 07:49:14 +0000
+++ Percona-Server/storage/innobase/include/trx0trx.h	2013-03-15 09:57:21 +0000
@@ -686,9 +686,6 @@
 	UT_LIST_BASE_NODE_T(lock_t)
 			trx_locks;	/*!< locks reserved by the transaction */
 	/*------------------------------*/
-	mem_heap_t*	global_read_view_heap;
-					/* memory heap for the global read
-					view */
 	read_view_t*	global_read_view;
 					/* consistent read view associated
 					to a transaction or NULL */
@@ -698,6 +695,7 @@
 					associated to a transaction (i.e.
 					same as global_read_view) or read view
 					associated to a cursor */
+	read_view_t*	prebuilt_view;	/* pre-built view array */
 	/*------------------------------*/
 	UT_LIST_BASE_NODE_T(trx_named_savept_t)
 			trx_savepoints;	/*!< savepoints set with SAVEPOINT ...,
 
=== modified file 'Percona-Server/storage/innobase/read/read0read.c'
--- Percona-Server/storage/innobase/read/read0read.c	2012-04-18 23:24:45 +0000
+++ Percona-Server/storage/innobase/read/read0read.c	2013-03-15 09:57:21 +0000
@@ -145,14 +145,27 @@
 read_view_create_low(
 /*=================*/
 	ulint		n,	/*!< in: number of cells in the trx_ids array */
-	mem_heap_t*	heap)	/*!< in: memory heap from which allocated */
+	read_view_t*	view)	/*!< in: pre-allocated view array or NULL if a
+				new one needs to be created */
 {
-	read_view_t*	view;
-
-	view = mem_heap_alloc(heap, sizeof(read_view_t));
+	if (view == NULL) {
+		view = ut_malloc(sizeof(read_view_t));
+		view->max_trx_ids = 0;
+		view->trx_ids = NULL;
+	}
+
+	if (UNIV_UNLIKELY(view->max_trx_ids < n)) {
+
+		/* avoid frequent reallocations by extending the array to the
+		desired size + 10% */
+
+		view->max_trx_ids = n + n / 10;
+		view->trx_ids = ut_realloc(view->trx_ids,
+					   view->max_trx_ids *
+					   sizeof *view->trx_ids);
+	}
 
 	view->n_trx_ids = n;
-	view->trx_ids = mem_heap_alloc(heap, n * sizeof *view->trx_ids);
 
 	return(view);
 }
@@ -169,8 +182,8 @@
 /*==============================*/
 	trx_id_t	cr_trx_id,	/*!< in: trx_id of creating
 					transaction, or 0 used in purge */
-	mem_heap_t*	heap)		/*!< in: memory heap from which
-					allocated */
+	read_view_t*	view)		/*!< in: pre-allocated view array or
+					NULL if a new one needs to be created */
 {
 	read_view_t*	old_view;
 	read_view_t*	view_copy;
@@ -185,7 +198,7 @@
 
 	if (old_view == NULL) {
 
-		return(read_view_open_now(cr_trx_id, heap));
+		return(read_view_open_now(cr_trx_id, view));
 	}
 
 	n = old_view->n_trx_ids;
@@ -196,7 +209,7 @@
 		needs_insert = FALSE;
 	}
 
-	view_copy = read_view_create_low(n, heap);
+	view_copy = read_view_create_low(n, view);
 
 	/* Insert the id of the creator in the right place of the descending
 	array of ids, if needs_insert is TRUE: */
@@ -251,16 +264,15 @@
 /*===============*/
 	trx_id_t	cr_trx_id,	/*!< in: trx_id of creating
 					transaction, or 0 used in purge */
-	mem_heap_t*	heap)		/*!< in: memory heap from which
-					allocated */
+	read_view_t*	view)		/*!< in: current read view or NULL if it
+					doesn't exist yet */
 {
-	read_view_t*	view;
 	trx_t*		trx;
 	ulint		n;
 
 	ut_ad(mutex_own(&kernel_mutex));
 
-	view = read_view_create_low(UT_LIST_GET_LEN(trx_sys->trx_list), heap);
+	view = read_view_create_low(UT_LIST_GET_LEN(trx_sys->trx_list), view);
 
 	view->creator_trx_id = cr_trx_id;
 	view->type = VIEW_NORMAL;
@@ -329,6 +341,23 @@
 }
 
 /*********************************************************************//**
+Frees resource allocated by a read view. */
+UNIV_INTERN
+void
+read_view_free(
+/*===========*/
+	read_view_t*	view)	/*< in: read view */
+{
+	ut_ad(mutex_own(&kernel_mutex));
+
+	if (view->trx_ids != NULL) {
+		ut_free(view->trx_ids);
+	}
+
+	ut_free(view);
+}
+
+/*********************************************************************//**
 Closes a consistent read view for MySQL. This function is called at an SQL
 statement end if the trx isolation level is <= TRX_ISO_READ_COMMITTED. */
 UNIV_INTERN
@@ -343,8 +372,6 @@
 
 	read_view_close(trx->global_read_view);
 
-	mem_heap_empty(trx->global_read_view_heap);
-
 	trx->read_view = NULL;
 	trx->global_read_view = NULL;
 
@@ -425,7 +452,7 @@
 	mutex_enter(&kernel_mutex);
 
 	curview->read_view = read_view_create_low(
-		UT_LIST_GET_LEN(trx_sys->trx_list), curview->heap);
+		UT_LIST_GET_LEN(trx_sys->trx_list), NULL);
 
 	view = curview->read_view;
 	view->creator_trx_id = cr_trx->id;
@@ -503,6 +530,8 @@
 	mutex_enter(&kernel_mutex);
 
 	read_view_close(curview->read_view);
+	read_view_free(curview->read_view);
+
 	trx->read_view = trx->global_read_view;
 
 	mutex_exit(&kernel_mutex);
 
=== modified file 'Percona-Server/storage/innobase/row/row0sel.c'
--- Percona-Server/storage/innobase/row/row0sel.c	2013-02-21 12:47:29 +0000
+++ Percona-Server/storage/innobase/row/row0sel.c	2013-03-15 09:57:21 +0000
@@ -4897,7 +4897,7 @@
 		    && !trx->read_view) {
 
 			trx->read_view = read_view_open_now(
-				trx->id, trx->global_read_view_heap);
+				trx->id, NULL);
 			trx->global_read_view = trx->read_view;
 		}
 	}
 
=== modified file 'Percona-Server/storage/innobase/trx/trx0purge.c'
--- Percona-Server/storage/innobase/trx/trx0purge.c	2013-02-18 04:48:10 +0000
+++ Percona-Server/storage/innobase/trx/trx0purge.c	2013-03-15 09:57:21 +0000
@@ -263,8 +263,9 @@
 
 	purge_sys->query = trx_purge_graph_build();
 
-	purge_sys->view = read_view_oldest_copy_or_open_new(0,
-							    purge_sys->heap);
+	purge_sys->prebuilt_view =
+		read_view_oldest_copy_or_open_new(0, NULL);
+	purge_sys->view = purge_sys->prebuilt_view;
 }
 
 /************************************************************************
@@ -289,6 +290,8 @@
 		mutex_enter(&kernel_mutex);
 
 		read_view_close(purge_sys->view);
+		read_view_free(purge_sys->prebuilt_view);
+		purge_sys->prebuilt_view = NULL;
 		purge_sys->view = NULL;
 
 		mutex_exit(&kernel_mutex);
@@ -1177,7 +1180,7 @@
 	}
 
 	purge_sys->view = read_view_oldest_copy_or_open_new(
-		0, purge_sys->heap);
+		0, purge_sys->prebuilt_view);
 
 	mutex_exit(&kernel_mutex);
 
 
=== modified file 'Percona-Server/storage/innobase/trx/trx0trx.c'
--- Percona-Server/storage/innobase/trx/trx0trx.c	2013-02-26 09:00:37 +0000
+++ Percona-Server/storage/innobase/trx/trx0trx.c	2013-03-15 09:57:21 +0000
@@ -190,9 +190,9 @@
 	trx->declared_to_be_inside_innodb = FALSE;
 	trx->n_tickets_to_enter_innodb = 0;
 
-	trx->global_read_view_heap = mem_heap_create(256);
 	trx->global_read_view = NULL;
 	trx->read_view = NULL;
+	trx->prebuilt_view = NULL;
 
 	trx->io_reads = 0;
 	trx->io_read = 0;
@@ -355,11 +355,12 @@
 
 	ut_a(UT_LIST_GET_LEN(trx->trx_locks) == 0);
 
-	if (trx->global_read_view_heap) {
-		mem_heap_free(trx->global_read_view_heap);
+	if (trx->prebuilt_view != NULL) {
+		read_view_free(trx->prebuilt_view);
 	}
 
 	trx->global_read_view = NULL;
+	trx->prebuilt_view = NULL;
 
 	ut_a(trx->read_view == NULL);
 
@@ -412,10 +413,6 @@
 		mem_heap_free(trx->lock_heap);
 	}
 
-	if (trx->global_read_view_heap) {
-		mem_heap_free(trx->global_read_view_heap);
-	}
-
 	ut_a(ib_vector_is_empty(trx->autoinc_locks));
 	ib_vector_free(trx->autoinc_locks);
 
@@ -1045,7 +1042,6 @@
 
 	if (trx->global_read_view) {
 		read_view_close(trx->global_read_view);
-		mem_heap_empty(trx->global_read_view_heap);
 		trx->global_read_view = NULL;
 	}
 
@@ -1187,8 +1183,9 @@
 	mutex_enter(&kernel_mutex);
 
 	if (!trx->read_view) {
-		trx->read_view = read_view_open_now(
-			trx->id, trx->global_read_view_heap);
+		trx->read_view = read_view_open_now(trx->id,
+						    trx->prebuilt_view);
+		trx->prebuilt_view = trx->read_view;
 		trx->global_read_view = trx->read_view;
 	}