InnoDB purge thread and other bg threads

in slow shutdown mode stop all bg threads that might generate
new undo records to purge before stopping purge threads.

storage/innobase/handler/ha_innodb.cc

@@ -345,6 +345,11 @@ thd_destructor_proxy(void *)
 		while (trx_sys_any_active_transactions()) {
 			os_thread_sleep(1000);
 		}
+
+		/* Some background threads might generate undo pages that will
+		need to be purged, so they have to be shut down before purge
+		threads if slow shutdown is requested.  */
+		srv_shutdown_bg_undo_sources();
 	}
 	srv_purge_wakeup();
 

storage/innobase/include/srv0start.h

@@ -88,6 +88,11 @@ Shuts down the Innobase database.
 dberr_t
 innobase_shutdown_for_mysql(void);
 
+/****************************************************************//**
+Shuts down background threads that can generate undo pages. */
+void
+srv_shutdown_bg_undo_sources(void);
+
 /********************************************************************
 Signal all per-table background threads to shutdown, and wait for them to do
 so. */

storage/innobase/srv/srv0start.cc

@@ -2769,6 +2769,21 @@ srv_fts_close(void)
 }
 #endif
 
+
+/****************************************************************//**
+Shuts down background threads that can generate undo pages. */
+void
+srv_shutdown_bg_undo_sources(void)
+/*===========================*/
+{
+	fts_optimize_shutdown();
+	dict_stats_shutdown();
+
+	/* Shutdown key rotation threads */
+	fil_crypt_threads_end();
+}
+
+
 /****************************************************************//**
 Shuts down the InnoDB database.
 @return DB_SUCCESS or error code */
@@ -2785,12 +2800,8 @@ innobase_shutdown_for_mysql(void)
 		return(DB_SUCCESS);
 	}
 
-	if (!srv_read_only_mode) {
-		fts_optimize_shutdown();
-		dict_stats_shutdown();
-
-		/* Shutdown key rotation threads */
-		fil_crypt_threads_end();
+	if (!srv_read_only_mode && srv_fast_shutdown) {
+		srv_shutdown_bg_undo_sources();
 	}
 
 	/* 1. Flush the buffer pool to disk, write the current lsn to