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------------------------------------------------------------ revno: 2617.69.37 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-next-bg46748 timestamp: Fri 2009-08-21 18:17:02 +0400 message: Fix for bug #46748 "Assertion in MDL_context::wait_for_locks() on INSERT + CREATE TRIGGER". Concurrent execution of statements involving stored functions or triggers which were using several tables and DDL statements which affected those tables on debug build of server might have led to assertion failures in MDL_context::wait_for_locks(). Non-debug build was not affected. The problem was that during back-off which happens when open_tables() encounters conflicting metadata lock for one of the tables being open we didn't reset MDL_request::ticket value for requests which correspond to tables from extended prelocking set. Since these requests are part of of list of requests to be waited for in Open_table_context this broke assumption that ticket value for them is 0 in MDL_context::wait_for_locks() and caused assertion failure. This fix ensures that close_tables_for_reopen(), which performs this back-off resets MDL_request::ticket value not only for tables directly used by the statement but also for tables from extended prelocking set, thus satisfying assumption described above. mysql-test/r/mdl_sync.result: Added test case for bug #46748 "Assertion in MDL_context::wait_for_locks() on INSERT + CREATE TRIGGER". mysql-test/t/mdl_sync.test: Added test case for bug #46748 "Assertion in MDL_context::wait_for_locks() on INSERT + CREATE TRIGGER". sql/sql_base.cc: Since metadata lock requests for tables from extended part of prelocking set are also part of list of requests to be waited for in Open_table_context in close_tables_for_reopen() we have to reset MDL_request::ticket values for them to assumptions in MDL_context::wait_for_locks().
65 lines
1.8 KiB
Plaintext
65 lines
1.8 KiB
Plaintext
SET DEBUG_SYNC= 'RESET';
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drop table if exists t1,t2,t3;
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create table t1 (i int);
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create table t2 (i int);
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connection: default
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lock tables t2 read;
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connection: con1
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set debug_sync='mdl_upgrade_shared_lock_to_exclusive SIGNAL parked WAIT_FOR go';
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alter table t1 rename t3;
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connection: default
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set debug_sync= 'now WAIT_FOR parked';
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connection: con2
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set debug_sync='mdl_acquire_exclusive_locks_wait SIGNAL go';
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drop table t1,t2;
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connection: con1
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connection: default
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unlock tables;
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connection: con2
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ERROR 42S02: Unknown table 't1'
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drop table t3;
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SET DEBUG_SYNC= 'RESET';
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#
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# Test for bug #46748 "Assertion in MDL_context::wait_for_locks()
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# on INSERT + CREATE TRIGGER".
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#
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drop tables if exists t1, t2, t3, t4, t5;
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# Let us simulate scenario in which we open some tables from extended
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# part of prelocking set but then encounter conflicting metadata lock,
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# so have to back-off and wait for it to go away.
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create table t1 (i int);
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create table t2 (j int);
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create table t3 (k int);
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create table t4 (l int);
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create trigger t1_bi before insert on t1 for each row
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insert into t2 values (new.i);
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create trigger t2_bi before insert on t2 for each row
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insert into t3 values (new.j);
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#
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# Switching to connection 'con1root'.
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lock tables t4 read;
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#
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# Switching to connection 'con2root'.
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# Send :
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rename table t3 to t5, t4 to t3;;
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#
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# Switching to connection 'default'.
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# Wait until the above RENAME TABLE adds pending requests for exclusive
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# metadata lock on its tables and blocks due to 't4' being used by LOCK
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# TABLES.
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# Send :
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insert into t1 values (1);;
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#
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# Switching to connection 'con1root'.
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# Wait until INSERT statement waits due to encountering pending
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# exclusive metadata lock on 't3'.
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unlock tables;
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#
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# Switching to connection 'con2root'.
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# Reap RENAME TABLE.
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#
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# Switching to connection 'default'.
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# Reap INSERT.
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# Clean-up.
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drop tables t1, t2, t3, t5;
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