Skip btr_search_latches[] in SHOW ENGINE INNODB STATUS

ha_print_info(): Remove. srv_printf_innodb_monitor(): Do not acquire btr_search_latches[] Add the equivalent functionality that was part of the non-debug version of ha_print_info().
MariaDB · Dec 12, 2017 · a3476a5 · a3476a5
1 parent 86c6926
commit a3476a5
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Showing 3 changed files with 22 additions and 68 deletions.
diff --git a/storage/innobase/ha/ha0ha.cc b/storage/innobase/ha/ha0ha.cc
@@ -489,62 +489,4 @@ ha_validate(
 	return(ok);
 }
 #endif /* defined UNIV_AHI_DEBUG || defined UNIV_DEBUG */
-
-/*************************************************************//**
-Prints info of a hash table. */
-void
-ha_print_info(
-/*==========*/
-	FILE*		file,	/*!< in: file where to print */
-	hash_table_t*	table)	/*!< in: hash table */
-{
-#ifdef UNIV_DEBUG
-/* Some of the code here is disabled for performance reasons in production
-builds, see http://bugs.mysql.com/36941 */
-#define PRINT_USED_CELLS
-#endif /* UNIV_DEBUG */
-
-#ifdef PRINT_USED_CELLS
-	hash_cell_t*	cell;
-	ulint		cells	= 0;
-	ulint		i;
-#endif /* PRINT_USED_CELLS */
-	ulint		n_bufs;
-
-	ut_ad(table);
-	ut_ad(table->magic_n == HASH_TABLE_MAGIC_N);
-#ifdef PRINT_USED_CELLS
-	for (i = 0; i < hash_get_n_cells(table); i++) {
-
-		cell = hash_get_nth_cell(table, i);
-
-		if (cell->node) {
-
-			cells++;
-		}
-	}
-#endif /* PRINT_USED_CELLS */
-
-	fprintf(file, "Hash table size %lu",
-		(ulong) hash_get_n_cells(table));
-
-#ifdef PRINT_USED_CELLS
-	fprintf(file, ", used cells %lu", (ulong) cells);
-#endif /* PRINT_USED_CELLS */
-
-	if (table->heaps == NULL && table->heap != NULL) {
-
-		/* This calculation is intended for the adaptive hash
-		index: how many buffer frames we have reserved? */
-
-		n_bufs = UT_LIST_GET_LEN(table->heap->base) - 1;
-
-		if (table->heap->free_block) {
-			n_bufs++;
-		}
-
-		fprintf(file, ", node heap has %lu buffer(s)\n",
-			(ulong) n_bufs);
-	}
-}
 #endif /* BTR_CUR_HASH_ADAPT */
diff --git a/storage/innobase/include/ha0ha.h b/storage/innobase/include/ha0ha.h
@@ -198,13 +198,6 @@ ha_validate(
 	ulint		start_index,	/*!< in: start index */
 	ulint		end_index);	/*!< in: end index */
 #endif /* defined UNIV_AHI_DEBUG || defined UNIV_DEBUG */
-/*************************************************************//**
-Prints info of a hash table. */
-void
-ha_print_info(
-/*==========*/
-	FILE*		file,	/*!< in: file where to print */
-	hash_table_t*	table);	/*!< in: hash table */
 
 /** The hash table external chain node */
 struct ha_node_t {

diff --git a/storage/innobase/srv/srv0srv.cc b/storage/innobase/srv/srv0srv.cc
@@ -1323,9 +1323,28 @@ srv_printf_innodb_monitor(
 
 #ifdef BTR_CUR_HASH_ADAPT
 	for (ulint i = 0; i < btr_ahi_parts; ++i) {
-		rw_lock_s_lock(btr_search_latches[i]);
-		ha_print_info(file, btr_search_sys->hash_tables[i]);
-		rw_lock_s_unlock(btr_search_latches[i]);
+		const hash_table_t* table = btr_search_sys->hash_tables[i];
+
+		ut_ad(table->magic_n == HASH_TABLE_MAGIC_N);
+		/* this is only used for buf_pool->page_hash */
+		ut_ad(!table->heaps);
+		/* this is used for the adaptive hash index */
+		ut_ad(table->heap);
+
+		const mem_heap_t* heap = table->heap;
+		/* The heap may change during the following call,
+		so the data displayed may be garbage. We intentionally
+		avoid acquiring btr_search_latches[] so that the
+		diagnostic output will not stop here even in case another
+		thread hangs while holding btr_search_latches[].
+
+		This should be safe from crashes, because
+		table->heap will be pointing to the same object
+		for the full lifetime of the server. Even during
+		btr_search_disable() the heap will stay valid. */
+		fprintf(file, "Hash table size " ULINTPF
+			", node heap has " ULINTPF " buffer(s)\n",
+			table->n_cells, heap->base.count - !heap->free_block);
 	}
 
 	fprintf(file,