Bug #39172 federated engine leaks memory in case of error opening the remote table

• Submitted: 2 Sep 2008 7:47
• Modified: 15 Jun 2009 7:42
• Reporter: Shane Bester (Platinum Quality Contributor)
• Status: Duplicate
• Category: MySQL Server: Federated storage engine
• Severity: S3 (Non-critical)
• Version: 5.0.66a, 5.0.70 (5.0 only)
• OS: Any
• Assigned to: Assigned Account
• CPU Architecture: Any
• Tags: federated, Leak, memory leak, valgrind

[2 Sep 2008 7:47] Shane Bester

Description:
when a federated table cannot be opened due to some error (such as network problems or somebody killed the connection, etc) there is a memory leak.

Valgrind outputs shows the location:

1) create or replace view v1 as select * from federated_table;

16,752 bytes in 349 blocks are definitely lost in loss record 7 of 7
 malloc (vg_replace_malloc.c:149)
 my_strdup_with_length (my_malloc.c:34)
 parse_url() (ha_federated.cc:571)
 get_share() (ha_federated.cc:1273)
 ha_federated::open() (ha_federated.cc:1400)
 handler::ha_open() (handler.cc:1409)
 openfrm() (table.cc:929)
 open_unireg_entry() (sql_base.cc:2545)
 open_table() (sql_base.cc:1919)
 open_tables() (sql_base.cc:2758)
 open_and_lock_tables() (sql_base.cc:3057)
 mysql_create_view() (sql_view.cc:470)

2) select * from federated_table:

3,024 bytes in 63 blocks are definitely lost in loss record 7 of 7
 malloc (vg_replace_malloc.c:149)
 my_strdup_with_length (my_malloc.c:34)
 parse_url() (ha_federated.cc:571)
 get_share() (ha_federated.cc:1273)
 ha_federated::open() (ha_federated.cc:1400)
 handler::ha_open() (handler.cc:1409)
 openfrm() (table.cc:929)
 open_unireg_entry() (sql_base.cc:2545)
 open_table() (sql_base.cc:1919)
 open_tables() (sql_base.cc:2758)
 open_and_lock_tables() (sql_base.cc:3057)
 mysql_execute_command() (sql_parse.cc:3110)

How to repeat:
check the code.  I will also upload a .c testcase to be run when mysqld is under valgrind.  The testcase will randomly kill connections to force failures in the code.

Suggested fix:
cleanup the memory in path of error execution.

[2 Sep 2008 7:58] MySQL Verification Team

testcase. run against  mysqld in valgrind.

Attachment: bug39172.c (text/plain), 7.23 KiB.

[15 Jun 2009 5:35] Anurag Shekhar

fix for bug#40875 has fixed this bug too.
This bug is not reproducible anymore.