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Fix Bug#40760 "set global innodb_thread_concurrency = 0;" is not safe

The config param innodb_thread_concurrency is dynamically set and is
read when a thread enters/exits innodb. If the value is changed between
the enter and exit time the behaviour becomes erratic.
The fix is not to use srv_thread_concurrency when exiting, instead use
the flag trx->declared_to_be_inside_innodb.

rb://57

Approved by: Marko
This commit is contained in:
inaam 2008-11-24 20:06:50 +00:00
parent fff52da321
commit 9b4f5f6f9f
3 changed files with 20 additions and 13 deletions
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2
handler/ha_innodb.cc
View file

@ -461,7 +461,7 @@ innodb_srv_conc_exit_innodb(
/*========================*/ /*========================*/
trx_t* trx) /* in: transaction handle */ trx_t* trx) /* in: transaction handle */
{ {
if (UNIV_LIKELY(!srv_thread_concurrency)) { if (UNIV_LIKELY(!trx->declared_to_be_inside_innodb)) {
return; return;
} }

27
srv/srv0srv.c
View file

@ -283,13 +283,16 @@ ulong srv_commit_concurrency = 0;
os_fast_mutex_t srv_conc_mutex; /* this mutex protects srv_conc data os_fast_mutex_t srv_conc_mutex; /* this mutex protects srv_conc data
structures */ structures */
lint srv_conc_n_threads = 0; /* number of OS threads currently lint srv_conc_n_threads = 0; /* number of transactions that
inside InnoDB; it is not an error have declared_to_be_inside_innodb
if this drops temporarily below zero set. It used to be a non-error
because we do not demand that every for this value to drop below
thread increments this, but a thread zero temporarily. This is no
waiting for a lock decrements this longer true. We'll, however,
temporarily */ keep the lint datatype to add
assertions to catch any corner
cases that we may have
missed. */
ulint srv_conc_n_waiting_threads = 0; /* number of OS threads waiting in the ulint srv_conc_n_waiting_threads = 0; /* number of OS threads waiting in the
FIFO for a permission to enter InnoDB FIFO for a permission to enter InnoDB
*/ */
@ -1020,6 +1023,8 @@ retry:
return; return;
} }
ut_ad(srv_conc_n_threads >= 0);
if (srv_conc_n_threads < (lint)srv_thread_concurrency) { if (srv_conc_n_threads < (lint)srv_thread_concurrency) {
srv_conc_n_threads++; srv_conc_n_threads++;
@ -1146,6 +1151,8 @@ srv_conc_force_enter_innodb(
return; return;
} }
ut_ad(srv_conc_n_threads >= 0);
os_fast_mutex_lock(&srv_conc_mutex); os_fast_mutex_lock(&srv_conc_mutex);
srv_conc_n_threads++; srv_conc_n_threads++;
@ -1167,11 +1174,6 @@ srv_conc_force_exit_innodb(
{ {
srv_conc_slot_t* slot = NULL; srv_conc_slot_t* slot = NULL;
if (UNIV_LIKELY(!srv_thread_concurrency)) {
return;
}
if (trx->mysql_thd != NULL if (trx->mysql_thd != NULL
&& thd_is_replication_slave_thread(trx->mysql_thd)) { && thd_is_replication_slave_thread(trx->mysql_thd)) {
@ -1185,6 +1187,7 @@ srv_conc_force_exit_innodb(
os_fast_mutex_lock(&srv_conc_mutex); os_fast_mutex_lock(&srv_conc_mutex);
ut_ad(srv_conc_n_threads > 0);
srv_conc_n_threads--; srv_conc_n_threads--;
trx->declared_to_be_inside_innodb = FALSE; trx->declared_to_be_inside_innodb = FALSE;
trx->n_tickets_to_enter_innodb = 0; trx->n_tickets_to_enter_innodb = 0;

4
trx/trx0trx.c
View file

@ -287,6 +287,10 @@ trx_free(
"InnoDB: inside InnoDB.\n", stderr); "InnoDB: inside InnoDB.\n", stderr);
trx_print(stderr, trx, 600); trx_print(stderr, trx, 600);
putc('\n', stderr); putc('\n', stderr);
/* This is an error but not a fatal error. We must keep
the counters like srv_conc_n_threads accurate. */
srv_conc_force_exit_innodb(trx);
} }
if (trx->n_mysql_tables_in_use != 0 if (trx->n_mysql_tables_in_use != 0