diff options
Diffstat (limited to 'sql/sql_class.cc')
| -rw-r--r-- | sql/sql_class.cc | 46 |
1 files changed, 43 insertions, 3 deletions
diff --git a/sql/sql_class.cc b/sql/sql_class.cc index 9a450f245be..3504b4fdea5 100644 --- a/sql/sql_class.cc +++ b/sql/sql_class.cc @@ -978,6 +978,14 @@ void add_diff_to_status(STATUS_VAR *to_var, STATUS_VAR *from_var, *(to++)+= *(from++) - *(dec++); } +#define SECONDS_TO_WAIT_FOR_KILL 2 +#if !defined(__WIN__) && defined(HAVE_SELECT) +/* my_sleep() can wait for sub second times */ +#define WAIT_FOR_KILL_TRY_TIMES 20 +#else +#define WAIT_FOR_KILL_TRY_TIMES 2 +#endif + void THD::awake(THD::killed_state state_to_set) { @@ -1032,12 +1040,35 @@ void THD::awake(THD::killed_state state_to_set) we issue a second KILL or the status it's waiting for happens). It's true that we have set its thd->killed but it may not see it immediately and so may have time to reach the cond_wait(). + + We have to do the loop with trylock, because if we would use + pthread_mutex_lock(), we can cause a deadlock as we are here locking + the mysys_var->mutex and mysys_var->current_mutex in a different order + than in the thread we are trying to kill. + We only sleep for 2 seconds as we don't want to have LOCK_delete + locked too long time. + + There is a small change we may not succeed in aborting a thread that + is not yet waiting for a mutex, but as this happens only for a + thread that was doing something else when the kill was issued and + which should detect the kill flag before it starts to wait, this + should be good enough. */ if (mysys_var->current_cond && mysys_var->current_mutex) { - pthread_mutex_lock(mysys_var->current_mutex); - pthread_cond_broadcast(mysys_var->current_cond); - pthread_mutex_unlock(mysys_var->current_mutex); + uint i; + for (i= 0; i < WAIT_FOR_KILL_TRY_TIMES * SECONDS_TO_WAIT_FOR_KILL; i++) + { + int ret= pthread_mutex_trylock(mysys_var->current_mutex); + pthread_cond_broadcast(mysys_var->current_cond); + if (!ret) + { + /* Signal is sure to get through */ + pthread_mutex_unlock(mysys_var->current_mutex); + break; + } + } + my_sleep(1000000L / WAIT_FOR_KILL_TRY_TIMES); } pthread_mutex_unlock(&mysys_var->mutex); } @@ -1073,6 +1104,15 @@ bool THD::store_globals() created in another thread */ thr_lock_info_init(&lock_info); + +#ifdef SAFE_MUTEX + /* Register order of mutex for wrong mutex deadlock detector */ + pthread_mutex_lock(&LOCK_delete); + pthread_mutex_lock(&mysys_var->mutex); + + pthread_mutex_unlock(&mysys_var->mutex); + pthread_mutex_unlock(&LOCK_delete); +#endif return 0; } |