mirror/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-02-01 11:31:51 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

branches/zip: Remove the additional check introduced in r6534 which tries

Browse source 
to check if the joining transaction has any other transactions waiting on
its locks. This optimization results in excessive deadlocks when running
Sysbench with a large number of threads. The function seems to return
FALSE positives.

rb://250
This commit is contained in:
sunny 2010-02-04 14:11:23 +00:00
parent e61c01eae7
commit 010da845ff
1 changed files with 0 additions and 63 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

63
lock/lock0lock.c
View file

@ -3311,64 +3311,6 @@ retry:
return(FALSE);
}
/********************************************************************//**
Check that no other transaction is waiting on this transaction's locks.
@return TRUE if some other transaction is waiting for this lock. */
static
ulint
lock_trx_has_no_waiters(
/*====================*/
const trx_t* trx) /*!< in: the transaction to check */
{
const lock_t* lock;
ut_ad(mutex_own(&kernel_mutex));
for (lock = UT_LIST_GET_FIRST(trx->trx_locks);
lock != NULL;
lock = UT_LIST_GET_NEXT(trx_locks, lock)) {
const lock_t* wait_lock = lock;
/* Look for all transactions that could be waiting on this
transaction's locks. For that we need to search forward. */
if (lock_get_type_low(lock) == LOCK_REC) {
ulint heap_no;
/* It's possible for heap_no to be undefined here.
This can happen during lock move from one page to
another when we split. */
heap_no = lock_rec_find_set_bit(lock);
do {
wait_lock = lock_rec_get_next(
heap_no, (lock_t*) wait_lock);
if (wait_lock != NULL
&& lock_has_to_wait(wait_lock, lock)) {
return(FALSE);
}
} while (wait_lock != NULL);
} else {
do {
wait_lock = UT_LIST_GET_NEXT(
un_member.tab_lock.locks, wait_lock);
if (wait_lock != NULL
&& lock_has_to_wait(wait_lock, lock) ) {
return(FALSE);
}
} while (wait_lock != NULL);
}
}
return(TRUE);
}
/********************************************************************//**
Looks recursively for a deadlock.
@return 0 if no deadlock found, LOCK_VICTIM_IS_START if there was a
@ -3404,16 +3346,11 @@ lock_deadlock_recursive(
/* We have already exhaustively searched the subtree starting
from this trx */
return(0);
} else if (lock_trx_has_no_waiters(trx)) {
/* If no other transaction is waiting for this transaction
to release its locks then no deadlock can occur. */
return(0);
}
*cost = *cost + 1;
if (lock_get_type_low(wait_lock) == LOCK_REC) {
ulint space;
ulint page_no;