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comments about mutexes in replication.

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Don't start the SQL slave thread with SQL_BIG_SELECTS;
it's better to inhibate max_join_size instead.
This commit is contained in:
guilhem@mysql.com
2003-08-25 16:20:21 +02:00
parent 73fe41f997
commit cc29458056
2 changed files with 30 additions and 7 deletions
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13
sql/slave.cc
View File

@@ -1991,13 +1991,12 @@ static int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type)
thd->priv_user = 0;
thd->slave_thread = 1;
thd->options = ((opt_log_slave_updates) ? OPTION_BIN_LOG:0) |
OPTION_AUTO_IS_NULL |
/*
It's nonsense to constraint the slave threads with max_join_size; if a
query succeeded on master, we HAVE to execute it.
*/
OPTION_BIG_SELECTS ;
OPTION_AUTO_IS_NULL;
/*
It's nonsense to constraint the slave threads with max_join_size; if a
query succeeded on master, we HAVE to execute it.
*/
thd->variables.max_join_size= HA_POS_ERROR;
thd->client_capabilities = CLIENT_LOCAL_FILES;
thd->real_id=pthread_self();
pthread_mutex_lock(&LOCK_thread_count);

24
sql/slave.h
View File

@@ -24,6 +24,30 @@
having to re-read the master updates.
*/
/*
MUTEXES in replication:
LOCK_active_mi: this is meant for multimaster, when we can switch from a
master to another. It protects active_mi. We don't care of it for the moment,
as active_mi never moves (it's created at startup and deleted at shutdown, and
not changed: it always points to the same MASTER_INFO struct), because we
don't have multimaster. So for the moment, mi does not move, and mi->rli does
not either.
In MASTER_INFO: run_lock, data_lock
run_lock protects all information about the run state: slave_running, and the
existence of the I/O thread (to stop/start it, you need this mutex).
data_lock protects some moving members of the struct: counters (log name,
position) and relay log (MYSQL_LOG object).
In RELAY_LOG_INFO: run_lock, data_lock
see MASTER_INFO
In MYSQL_LOG: LOCK_log, LOCK_index of the binlog and the relay log
LOCK_log: when you write to it. LOCK_index: when you create/delete a binlog
(so that you have to update the .index file).
*/
extern ulong slave_net_timeout, master_retry_count;
extern MY_BITMAP slave_error_mask;
extern bool use_slave_mask;