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, 2 insertions, 2 deletions

diff --git a/sql/slave.cc b/sql/slave.cc
index 2e4642d179e..af53bc65c0e 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -1480,7 +1480,7 @@ static void write_ignored_events_info_to_relay_log(THD *thd, Master_info *mi)
                    " to the relay log, SHOW SLAVE STATUS may be"
                    " inaccurate");
       rli->relay_log.harvest_bytes_written(&rli->log_space_total);
-      if (flush_master_info(mi, 1))
+      if (flush_master_info(mi, TRUE, TRUE))
         sql_print_error("Failed to flush master info file");
       delete ev;
     }
@@ -2731,7 +2731,7 @@ Stopping slave I/O thread due to out-of-memory error from master");
                    "could not queue event from master");
         goto err;
       }
-      if (flush_master_info(mi, 1))
+      if (flush_master_info(mi, TRUE, TRUE))
       {
         sql_print_error("Failed to flush master info file");
         goto err;