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| author | Jon Olav Hauglid <jon.hauglid@sun.com> | 2010-02-11 11:23:39 +0100 |
|---|---|---|
| committer | Jon Olav Hauglid <jon.hauglid@sun.com> | 2010-02-11 11:23:39 +0100 |
| commit | 5bb67f34b864ea40c74dc729fdc960de13718ab3 (patch) | |
| tree | 61c2376a790a37e251fcfa30ba118b660e25e60d /sql/sys_vars.cc | |
| parent | 65808c91df1d5e9282e2383bd8378d7cd40139d9 (diff) | |
| download | mariadb-git-5bb67f34b864ea40c74dc729fdc960de13718ab3.tar.gz | |
Bug #45225 Locking: hang if drop table with no timeout
This patch introduces timeouts for metadata locks.
The timeout is specified in seconds using the new dynamic system
variable "lock_wait_timeout" which has both GLOBAL and SESSION
scopes. Allowed values range from 1 to 31536000 seconds (= 1 year).
The default value is 1 year.
The new server parameter "lock-wait-timeout" can be used to set
the default value parameter upon server startup.
"lock_wait_timeout" applies to all statements that use metadata locks.
These include DML and DDL operations on tables, views, stored procedures
and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH
READ LOCK and HANDLER statements.
The patch also changes thr_lock.c code (table data locks used by MyISAM
and other simplistic engines) to use the same system variable.
InnoDB row locks are unaffected.
One exception to the handling of the "lock_wait_timeout" variable
is delayed inserts. All delayed inserts are executed with a timeout
of 1 year regardless of the setting for the global variable. As the
connection issuing the delayed insert gets no notification of
delayed insert timeouts, we want to avoid unnecessary timeouts.
It's important to note that the timeout value is used for each lock
acquired and that one statement can take more than one lock.
A statement can therefore block for longer than the lock_wait_timeout
value before reporting a timeout error. When lock timeout occurs,
ER_LOCK_WAIT_TIMEOUT is reported.
Test case added to lock_multi.test.
Diffstat (limited to 'sql/sys_vars.cc')
| -rw-r--r-- | sql/sys_vars.cc | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc index 73d01f5341d..085e8b8ee1e 100644 --- a/sql/sys_vars.cc +++ b/sql/sys_vars.cc @@ -853,6 +853,12 @@ static Sys_var_mybool Sys_local_infile( "local_infile", "Enable LOAD DATA LOCAL INFILE", GLOBAL_VAR(opt_local_infile), CMD_LINE(OPT_ARG), DEFAULT(TRUE)); +static Sys_var_ulong Sys_lock_wait_timeout( + "lock_wait_timeout", + "Timeout in seconds to wait for a lock before returning an error.", + SESSION_VAR(lock_wait_timeout), CMD_LINE(REQUIRED_ARG), + VALID_RANGE(1, LONG_TIMEOUT), DEFAULT(LONG_TIMEOUT), BLOCK_SIZE(1)); + #ifdef HAVE_MLOCKALL static Sys_var_mybool Sys_locked_in_memory( "locked_in_memory", |