Description:
This snippet of
bool dispatch_command(enum enum_server_command command, THD *thd,
char* packet, uint packet_length)
{
NET *net= &thd->net;
bool error= 0;
DBUG_ENTER("dispatch_command");
if (thd->killed == THD::KILL_QUERY || thd->killed == THD::KILL_BAD_DATA)
{
thd->killed= THD::NOT_KILLED;
thd->mysys_var->abort= 0;
}
shows thd->killed is reset possibly with the intention to clear up
a potential previous statement's killed status.
However, the connection handle may wipe out the killed status belonging to
the current just have been started statement, not the previous one (!), as `dispatch_command' is fed with
a query by `do_command' reader:
#0 dispatch_command (command=COM_QUERY, thd ...)
#1 do_command (thd=0x8cb12a0)
#2 handle_one_connection (arg=0x8cb12a0)
not the previous one.
There is evidence it's practically happens.
from:
https://intranet.mysql.com/secure/pushbuild/getlog.pl?dir=mysql-5.0-rpl&entry=aelkin@koti....
binlog_killed [ fail ]
--- C:/cygwin/home/pushbuild/pb3/pb/mysql-5.0-rpl/178/mysql-5.0.52-pb178/mysql-test/r/binlog_killed.result 2007-11-06 18:21:07.000000000 +0300
+++ C:\cygwin\home\pushbuild\pb3\pb\mysql-5.0-rpl\178\mysql-5.0.52-pb178\mysql-test\r\binlog_killed.reject 2007-11-06 19:08:57.453125000 +0300
@@ -32,7 +32,6 @@
select * from t1 order by a /* must be the same as before (1,1),(2,2) */;
a b
1 1
-2 2
drop table if exists t4;
create table t4 (a int, b int) engine=innodb;
insert into t4 values (3, 3);
@@ -46,7 +45,6 @@
select * from t1 /* must be the same as before (1,1),(2,2) */;
a b
1 1
-2 2
This happens when the following snippet of the test works:
connection con1;
begin; delete from t1 where a=2;
connection con2;
let $ID= `select connection_id()`;
send delete from t1 where a=2;
connection con1;
--replace_result $ID ID
eval kill query $ID;
rollback;
connection con2;
--error 0,ER_QUERY_INTERRUPTED
reap;
select * from t1 order by a /* must be the same as before (1,1),(2,2) */;
The assertion of the last select does not hold.
How to repeat:
run binlog_killed or its parts like in the HOW-2-REPEAT on slow env.
Suggested fix:
clean up the killed status of a statement at the end of the statement not at the beginning of the successive one.
Description: This snippet of bool dispatch_command(enum enum_server_command command, THD *thd, char* packet, uint packet_length) { NET *net= &thd->net; bool error= 0; DBUG_ENTER("dispatch_command"); if (thd->killed == THD::KILL_QUERY || thd->killed == THD::KILL_BAD_DATA) { thd->killed= THD::NOT_KILLED; thd->mysys_var->abort= 0; } shows thd->killed is reset possibly with the intention to clear up a potential previous statement's killed status. However, the connection handle may wipe out the killed status belonging to the current just have been started statement, not the previous one (!), as `dispatch_command' is fed with a query by `do_command' reader: #0 dispatch_command (command=COM_QUERY, thd ...) #1 do_command (thd=0x8cb12a0) #2 handle_one_connection (arg=0x8cb12a0) not the previous one. There is evidence it's practically happens. from: https://intranet.mysql.com/secure/pushbuild/getlog.pl?dir=mysql-5.0-rpl&entry=aelkin@koti.... binlog_killed [ fail ] --- C:/cygwin/home/pushbuild/pb3/pb/mysql-5.0-rpl/178/mysql-5.0.52-pb178/mysql-test/r/binlog_killed.result 2007-11-06 18:21:07.000000000 +0300 +++ C:\cygwin\home\pushbuild\pb3\pb\mysql-5.0-rpl\178\mysql-5.0.52-pb178\mysql-test\r\binlog_killed.reject 2007-11-06 19:08:57.453125000 +0300 @@ -32,7 +32,6 @@ select * from t1 order by a /* must be the same as before (1,1),(2,2) */; a b 1 1 -2 2 drop table if exists t4; create table t4 (a int, b int) engine=innodb; insert into t4 values (3, 3); @@ -46,7 +45,6 @@ select * from t1 /* must be the same as before (1,1),(2,2) */; a b 1 1 -2 2 This happens when the following snippet of the test works: connection con1; begin; delete from t1 where a=2; connection con2; let $ID= `select connection_id()`; send delete from t1 where a=2; connection con1; --replace_result $ID ID eval kill query $ID; rollback; connection con2; --error 0,ER_QUERY_INTERRUPTED reap; select * from t1 order by a /* must be the same as before (1,1),(2,2) */; The assertion of the last select does not hold. How to repeat: run binlog_killed or its parts like in the HOW-2-REPEAT on slow env. Suggested fix: clean up the killed status of a statement at the end of the statement not at the beginning of the successive one.