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Bug #18808072 MYSQLBINLOG USES LOCALTIME() TO PRINT EVENTS, CAUSES KERNEL MUTEX CONTENTION

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Problem: For every event read, mysqlbinlog calls localtime() which in turn
calls stat(/etc/localtime) which is causing kernel mutex contention.

Analysis and Fix:
localtime() calls stat(/etc/localtime) for every instance of the call
where as localtime_r() the reentrant version was optimized to store
the read only tz internal structure. Hence it will not call
stat(/etc/localtime). It will call only once at the beginning.
The mysql server is calling localtime_r() and mysqlbinlog tool is
one place where we are still using localtime().

Once the process (mysqlbinlog) is started if timezone is changed
it will be not picked up the the process and it will continue
with the same values as the beginning of the process. This
behavior is in-lined with mysql server.

Also adding localtime_r() and gmtime_r() support for windows.
This commit is contained in:
Venkatesh Duggirala
2014-10-08 21:54:35 +05:30
parent 0d0c59ff80
commit a3cc647dbd
5 changed files with 19 additions and 35 deletions
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3
client/mysqlbinlog.cc
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@ -1,5 +1,5 @@
/*
Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@ -2102,6 +2102,7 @@ int main(int argc, char** argv)
DBUG_PROCESS(argv[0]);
my_init_time(); // for time functions
tzset(); // set tzname
if (load_defaults("my", load_default_groups, &argc, &argv))
exit(1);