Fixed issue on xtradb shutdown merge error. Multi-threaded flush threads

where not shut down properly.

storage/innobase/buf/buf0flu.cc

@@ -1973,6 +1973,10 @@ void pgcomp_init(void)
 {
 	os_fast_mutex_init(PFS_NOT_INSTRUMENTED, &pgcomp_mtx);
 }
+void pgcomp_deinit(void)
+{
+	os_fast_mutex_free(&pgcomp_mtx);
+}
 
 /*******************************************************************//**
 Multi-threaded version of buf_flush_list

storage/innobase/srv/srv0start.cc

@@ -1444,6 +1444,7 @@ extern void buf_flush_end(buf_pool_t* buf_pool, enum buf_flush flush_type);
 extern void buf_flush_common(enum buf_flush flush_type, ulint page_count);
 extern ulint buf_flush_batch(buf_pool_t* buf_pool, enum buf_flush flush_type, ulint min_n, lsn_t lsn_limit);
 extern void pgcomp_init(void);
+extern void pgcomp_deinit(void);
 
 typedef enum wrk_status {
 	WRK_ITEM_SET=0,     // wrk-item is set
@@ -3277,6 +3278,9 @@ innobase_shutdown_for_mysql(void)
 		fprintf(stderr, "%s:%d os_thread_count:%lu \n", __FUNCTION__, __LINE__, os_thread_count);
 #endif
 
+		/* h. Remove the mutex */
+		pgcomp_deinit();
+
 		os_mutex_enter(os_sync_mutex);
 
 		if (os_thread_count == 0) {

storage/xtradb/buf/buf0flu.cc

@@ -1931,6 +1931,21 @@ buf_flush_wait_batch_end(
 }
 
 /* JAN: TODO: */
+
+void buf_pool_enter_LRU_mutex(
+	buf_pool_t*    buf_pool)
+{
+	ut_ad(!mutex_own(&buf_pool->LRU_list_mutex));
+	mutex_enter(&buf_pool->LRU_list_mutex);
+}
+
+void buf_pool_exit_LRU_mutex(
+	buf_pool_t*    buf_pool)
+{
+	ut_ad(mutex_own(&buf_pool->LRU_list_mutex));
+	mutex_exit(&buf_pool->LRU_list_mutex);
+}
+
 /*******************************************************************//**
 This utility flushes dirty blocks from the end of the LRU list and also
 puts replaceable clean pages from the end of the LRU list to the free
@@ -2053,6 +2068,11 @@ void pgcomp_init(void)
 	os_fast_mutex_init(PFS_NOT_INSTRUMENTED, &pgcomp_mtx);
 }
 
+void pgcomp_deinit(void)
+{
+	os_fast_mutex_free(&pgcomp_mtx);
+}
+
 /*******************************************************************//**
 Multi-threaded version of buf_flush_list
 */
@@ -2096,11 +2116,11 @@ pgcomp_buf_flush_list(
 #ifdef UNIV_DEBUG
 	gettimeofday(&p_start_time, 0x0);
 #endif
-	os_fast_mutex_lock(&pgcomp_mtx);
+	// os_fast_mutex_lock(&pgcomp_mtx);
 	pgcomp_flush_work_items(srv_buf_pool_instances,
                 cnt_flush, BUF_FLUSH_LIST,
                 min_n, lsn_limit);
-	os_fast_mutex_unlock(&pgcomp_mtx);
+	// os_fast_mutex_unlock(&pgcomp_mtx);
 
 	for (i = 0; i < srv_buf_pool_instances; i++) {
 		if (n_processed) {

storage/xtradb/srv/srv0start.cc

@@ -1520,6 +1520,9 @@ extern void buf_flush_common(buf_flush_t flush_type, ulint page_count);
 extern ulint buf_flush_batch(buf_pool_t* buf_pool, buf_flush_t flush_type, ulint min_n, lsn_t lsn_limit, bool limited_lru_scan,
 flush_counters_t* n);
 extern void pgcomp_init(void);
+extern void pgcomp_deinit(void);
+extern void buf_pool_enter_LRU_mutex(buf_pool_t*);
+extern void buf_pool_exit_LRU_mutex(buf_pool_t*);
 
 typedef enum wrk_status {
 	WRK_ITEM_SET=0,     // wrk-item is set
@@ -1555,7 +1558,6 @@ typedef struct wr_tsk {
 	lsn_t	    lsn_limit;//lsn limit for the buffer-pool flush operation
 } wr_tsk_t;
 
-
 typedef struct rd_tsk {
 	void        *page_pool; //list of pages to decompress;
 } rd_tsk_t;
@@ -1665,9 +1667,9 @@ int flush_pool_instance(wrk_t *wi)
         	/* srv_LRU_scan_depth can be arbitrarily large value.
         	 * We cap it with current LRU size.
         	 */
-        	buf_pool_mutex_enter(wi->wr.buf_pool);
+        	buf_pool_enter_LRU_mutex(wi->wr.buf_pool);
         	wi->wr.min = UT_LIST_GET_LEN(wi->wr.buf_pool->LRU);
-        	buf_pool_mutex_exit(wi->wr.buf_pool);
+        	buf_pool_exit_LRU_mutex(wi->wr.buf_pool);
         	wi->wr.min = ut_min(srv_LRU_scan_depth,wi->wr.min);
     	}
 
@@ -3407,8 +3409,20 @@ innobase_shutdown_for_mysql(void)
 		logs_empty_and_mark_files_at_shutdown() and should have
 		already quit or is quitting right now. */
 
+		/* g. Exit the multi threaded flush threads */
+
+		page_comp_io_thread_exit();
+
+#ifdef UNIV_DEBUG
+		fprintf(stderr, "%s:%d os_thread_count:%lu \n", __FUNCTION__, __LINE__, os_thread_count);
+#endif
+
+		/* h. Remove the mutex */
+		pgcomp_deinit();
+
 		os_mutex_enter(os_sync_mutex);
 
+
 		if (os_thread_count == 0) {
 			/* All the threads have exited or are just exiting;
 			NOTE that the threads may not have completed their