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  1. MariaDB Server
  2. MDEV-11775

sys_vars.thread_cache_size_func failed in buildbot with wrong result

Details

    • Bug
    • Status: Closed (View Workflow)
    • Minor
    • Resolution: Won't Fix
    • 10.0(EOL), 10.1(EOL)
    • N/A
    • Tests
    • None

    Description

      http://buildbot.askmonty.org/buildbot/builders/kvm-deb-yakkety-x86/builds/39/steps/test_4/logs/stdio

      sys_vars.thread_cache_size_func          w4 [ fail ]
              Test ended at 2016-10-25 11:59:28
       
      CURRENT_TEST: sys_vars.thread_cache_size_func
      --- /usr/share/mysql/mysql-test/suite/sys_vars/r/thread_cache_size_func.result	2016-10-25 09:52:02.000000000 -0400
      +++ /dev/shm/var/4/log/thread_cache_size_func.reject	2016-10-25 11:59:28.820780019 -0400
      @@ -18,7 +18,7 @@
       ** Disconnecting conn1,conn2,conn3,conn4 **
       SHOW STATUS LIKE 'Threads_cached';
       Variable_name	Value
      -Threads_cached	3
      +Threads_cached	1
       3 Expected
       SET @@GLOBAL.thread_cache_size= 1;
       ** Connecting conn1 using username 'root' **
       
      mysqltest: Result content mismatch
      

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            This is caused by incorrect testcase sync: the testcase disconnects, waits for the threads disappear from the processlist, then checks the status variable. But a disconnecting thread first removes itself from the processlist, and becomes cached only later, creating a race condition.

            A proper fix appears to drop processlist checks and SHOW STATUS, and wait for Threads_cached to become desired value by wait_for_status_var.inc, see https://github.com/percona/percona-server/pull/1337

            laurynas Laurynas Biveinis added a comment - This is caused by incorrect testcase sync: the testcase disconnects, waits for the threads disappear from the processlist, then checks the status variable. But a disconnecting thread first removes itself from the processlist, and becomes cached only later, creating a race condition. A proper fix appears to drop processlist checks and SHOW STATUS, and wait for Threads_cached to become desired value by wait_for_status_var.inc, see https://github.com/percona/percona-server/pull/1337

            Recent occurrence in 10.1:
            http://buildbot.askmonty.org/buildbot/builders/kvm-deb-wheezy-x86/builds/4633/steps/mtr/logs/stdio

            sys_vars.thread_cache_size_func          w1 [ fail ]
                    Test ended at 2017-05-23 05:28:55
             
            CURRENT_TEST: sys_vars.thread_cache_size_func
            --- /usr/share/mysql/mysql-test/suite/sys_vars/r/thread_cache_size_func.result	2017-05-23 03:48:45.000000000 -0400
            +++ /run/shm/var/1/log/thread_cache_size_func.reject	2017-05-23 05:28:55.080905256 -0400
            @@ -18,7 +18,7 @@
             ** Disconnecting conn1,conn2,conn3,conn4 **
             SHOW STATUS LIKE 'Threads_cached';
             Variable_name	Value
            -Threads_cached	3
            +Threads_cached	0
             3 Expected
             SET @@GLOBAL.thread_cache_size= 1;
             ** Connecting conn1 using username 'root' **
             
            mysqltest: Result content mismatch
            

            elenst Elena Stepanova added a comment - Recent occurrence in 10.1: http://buildbot.askmonty.org/buildbot/builders/kvm-deb-wheezy-x86/builds/4633/steps/mtr/logs/stdio sys_vars.thread_cache_size_func w1 [ fail ] Test ended at 2017-05-23 05:28:55   CURRENT_TEST: sys_vars.thread_cache_size_func --- /usr/share/mysql/mysql-test/suite/sys_vars/r/thread_cache_size_func.result 2017-05-23 03:48:45.000000000 -0400 +++ /run/shm/var/1/log/thread_cache_size_func.reject 2017-05-23 05:28:55.080905256 -0400 @@ -18,7 +18,7 @@ ** Disconnecting conn1,conn2,conn3,conn4 ** SHOW STATUS LIKE 'Threads_cached'; Variable_name Value -Threads_cached 3 +Threads_cached 0 3 Expected SET @@GLOBAL.thread_cache_size= 1; ** Connecting conn1 using username 'root' **   mysqltest: Result content mismatch

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              elenst Elena Stepanova
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                Updated:
                Resolved:

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