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| author | prabakaran thirumalai <prabakaran.thirumalai@oracle.com> | 2013-07-30 09:44:11 +0530 |
|---|---|---|
| committer | prabakaran thirumalai <prabakaran.thirumalai@oracle.com> | 2013-07-30 09:44:11 +0530 |
| commit | 592a2b2a94c85fbf1199276789efd32c73ab41f1 (patch) | |
| tree | 6a47a11f1578933d54874fd12551fd481d57f837 /sql/sql_class.cc | |
| parent | 1c4a3c52fdacd583d73c3df6c0fb1f975ea098c2 (diff) | |
| download | mariadb-git-592a2b2a94c85fbf1199276789efd32c73ab41f1.tar.gz | |
Bug#17083851 BACKPORT BUG#11765744 TO 5.1, 5.5 AND 5.6
Description:
Original fix Bug#11765744 changed mutex to read write lock
to avoid multiple recursive lock acquire operation on
LOCK_status mutex.
On Windows, locking read-write lock recursively is not safe.
Slim read-write locks, which MySQL uses if they are supported by
Windows version, do not support recursion according to their
documentation. For our own implementation of read-write lock,
which is used in cases when Windows version doesn't support SRW,
recursive locking of read-write lock can easily lead to deadlock
if there are concurrent lock requests.
Fix:
This patch reverts the previous fix for bug#11765744 that used
read-write locks. Instead problem of recursive locking for
LOCK_status mutex is solved by tracking recursion level using
counter in THD object and acquiring lock only once when we enter
fill_status() function first time.
Diffstat (limited to 'sql/sql_class.cc')
| -rw-r--r-- | sql/sql_class.cc | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/sql/sql_class.cc b/sql/sql_class.cc index 80bd4eff457..d71da6403ae 100644 --- a/sql/sql_class.cc +++ b/sql/sql_class.cc @@ -605,6 +605,7 @@ THD::THD() Open_tables_state(refresh_version), rli_fake(NULL), rli_slave(NULL), lock_id(&main_lock_id), user_time(0), in_sub_stmt(0), + fill_status_recursion_level(0), sql_log_bin_toplevel(false), binlog_table_maps(0), binlog_flags(0UL), table_map_for_update(0), |