From e8049f064971a910599396e4eb77e8ffe3bb8ecd Mon Sep 17 00:00:00 2001
From: "guilhem@mysql.com" <>
Date: Sun, 14 Nov 2004 17:45:37 +0100
Subject: [PATCH] Try to lower the probability of a stall of mysqldump AND most
 client connections, when mysqldump does a FLUSH TABLES WITH READ LOCK (doing
 FLUSH TABLES first).

---
 client/mysqldump.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/client/mysqldump.c b/client/mysqldump.c
index 540f0d78c50..498a10041a9 100644
--- a/client/mysqldump.c
+++ b/client/mysqldump.c
@@ -2050,8 +2050,18 @@ static int do_show_master_status(MYSQL *mysql_con)
 
 static int do_flush_tables_read_lock(MYSQL *mysql_con)
 {
+  /*
+    We do first a FLUSH TABLES. If a long update is running, the FLUSH TABLES
+    will wait but will not stall the whole mysqld, and when the long update is
+    done the FLUSH TABLES WITH READ LOCK will start and succeed quickly. So,
+    FLUSH TABLES is to lower the probability of a stage where both mysqldump
+    and most client connections are stalled. Of course, if a second long
+    update starts between the two FLUSHes, we have that bad stall.
+  */
   return 
-    mysql_query_with_error_report(mysql_con, 0, "FLUSH TABLES WITH READ LOCK");
+    ( mysql_query_with_error_report(mysql_con, 0, "FLUSH TABLES") ||
+      mysql_query_with_error_report(mysql_con, 0,
+                                    "FLUSH TABLES WITH READ LOCK") );
 }