From 63e6005ac40e5aa894e770287d8bcf45aa9f5198 Mon Sep 17 00:00:00 2001 From: Alexander Nozdrin Date: Fri, 30 Apr 2010 16:12:41 +0400 Subject: Patch for Bug#52356: query_cache_debug fails on Linux. There were two problems here: 1. misleading error message 2. abusing KILL QUERY in the test case 1. The server reported "'DELETE FROM t1' failed: 1689: Wait on a lock was aborted due to a pending exclusive lock", while the proper error message should be "'DELETE FROM t1' failed: 1317: Query execution was interrupted". The problem is that the server has two different flags for signalling that a query is being killed: THD::killed and mysys_var::abort. The test case triggers a race: sometimes mysys_var::abort is set earlier than THD::killed. That leads to the following situation: - thr_lock() checks mysys_var::abort and returns error status, since mysys_var::abort is set; - the caller (mysql_lock_tables()) gets an error from thr_lock(), but THD::killed is not set, so it decides that thr_lock() couldn't get a lock due to a pending exclusive lock. This is a known issue with the server and it's not going to be fixed soon. 5.5 differs from 5.1 here as follows: when thr_lock() returns an error: - 5.1 continues trying thr_lock() until success; - 5.5 propagates the error 2. The test case uses KILL QUERY is a highly concurent environment. The fix is to wait for the dying statement to rest in peace before executing another DELETE FROM t1. --- mysql-test/t/query_cache_debug.test | 3 +++ 1 file changed, 3 insertions(+) (limited to 'mysql-test/t/query_cache_debug.test') diff --git a/mysql-test/t/query_cache_debug.test b/mysql-test/t/query_cache_debug.test index d30cd458e99..ce62b931a93 100644 --- a/mysql-test/t/query_cache_debug.test +++ b/mysql-test/t/query_cache_debug.test @@ -221,6 +221,9 @@ KILL QUERY @thread_id; SELECT SQL_NO_CACHE id FROM information_schema.processlist WHERE state='wait_in_query_cache_invalidate2' LIMIT 1 INTO @flush_thread_id; KILL QUERY @flush_thread_id; +LET $wait_condition= SELECT SQL_NO_CACHE COUNT(*) = 1 FROM INFORMATION_SCHEMA.PROCESSLIST WHERE Id = @flush_thread_id AND Command = 'Sleep'; +--source include/wait_condition.inc + --echo ** --echo ************************************************************************* --echo ** No tables should be locked -- cgit v1.2.1