BUG#53657: Slave crashed with error 22 when trying to lock mutex

           at mf_iocache.c, line 1722

The slave crashed while two threads: IO thread and user thread
raced for the same mutex (the append_buffer_lock protecting the
relay log's IO_CACHE). The IO thread was trying to flush the
cache, and for that was grabbing the append_buffer_lock. 

However, the other thread was closing and reopening the relay log
when the IO thread tried to lock. Closing and reopening the log
includes destroying and reinitialising the IO_CACHE
mutex. Therefore, the IO thread tried to lock a destroyed mutex.

We fix this by backporting patch for BUG#50364 which fixed this
bug in mysql server 5.5+. The patch deploys missing
synchronization when flush_master_info is called and the relay
log is flushed by the IO thread. In detail the patch backports
revision (from mysql-trunk):
- luis.soares@sun.com-20100203165617-b1yydr0ee24ycpjm

This patch already includes the post-push fix also in BUG#50364:
- luis.soares@sun.com-20100222002629-0cijwqk6baxhj7gr

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/repl_failsafe.cc b/sql/repl_failsafe.cc
index c6a05e93bf4..c25d43ea5ba 100644
--- a/sql/repl_failsafe.cc
+++ b/sql/repl_failsafe.cc
@@ -976,7 +976,7 @@ bool load_master_data(THD* thd)
           host was specified; there could have been a problem when replication
           started, which led to relay log's IO_CACHE to not be inited.
         */
-        if (flush_master_info(active_mi, 0))
+        if (flush_master_info(active_mi, FALSE, FALSE))
           sql_print_error("Failed to flush master info file");
       }
       mysql_free_result(master_status_res);