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  1. MariaDB Server
  2. MDEV-4520

Assertion `0' fails in Query_cache::end_of_result on concurrent drop event and event execution



    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Fixed
    • 10.0.2, 5.5.31
    • 10.0.3, 5.5.32
    • None
    • None


      Version: '5.5.31-MariaDB-valgrind-max-debug-log'  socket: '/data/repo/bzr/5.5/mysql-test/var/tmp/mysqld.1.sock'  port: 16000  Source distribution
      130514  3:43:29 [Note] Event Scheduler: scheduler thread started with id 8
      mysqld: /home/elenst/bzr/5.5/sql/sql_cache.cc:1211: void Query_cache::end_of_result(THD*): Assertion `0' failed.
      130514  3:43:29 [ERROR] mysqld got signal 6 ;

      #7  0x00007f1574b1d192 in __GI___assert_fail (assertion=0xd615d2 "0", file=0xd61058 "/home/elenst/bzr/5.5/sql/sql_cache.cc", line=1211, function=0xd63b40 "void Query_cache::end_of_result(THD*)") at assert.c:103
      #8  0x00000000005c7837 in Query_cache::end_of_result (this=0x14fd520, thd=0x7f1540001cc0) at /home/elenst/bzr/5.5/sql/sql_cache.cc:1211
      #9  0x000000000090e66b in sp_instr_stmt::execute (this=0x7f1544002c98, thd=0x7f1540001cc0, nextp=0x7f1565ef34f8) at /home/elenst/bzr/5.5/sql/sp_head.cc:3134
      #10 0x000000000090a22a in sp_head::execute (this=0x7f15440033b8, thd=0x7f1540001cc0, merge_da_on_success=true) at /home/elenst/bzr/5.5/sql/sp_head.cc:1428
      #11 0x000000000090c0b8 in sp_head::execute_procedure (this=0x7f15440033b8, thd=0x7f1540001cc0, args=0x7f1565ef38a0) at /home/elenst/bzr/5.5/sql/sp_head.cc:2185
      #12 0x00000000006fad17 in Event_job_data::execute (this=0x7f1565ef3d10, thd=0x7f1540001cc0, drop=false) at /home/elenst/bzr/5.5/sql/event_data_objects.cc:1433
      #13 0x000000000094ec25 in Event_worker_thread::run (this=0x7f1565ef3e4f, thd=0x7f1540001cc0, event=0x7f1540001bf0) at /home/elenst/bzr/5.5/sql/event_scheduler.cc:317
      #14 0x000000000094ea9d in event_worker_thread (arg=0x7f1540001bf0) at /home/elenst/bzr/5.5/sql/event_scheduler.cc:274
      #15 0x0000000000977c3e in pfs_spawn_thread (arg=0x7f154000b190) at /home/elenst/bzr/5.5/storage/perfschema/pfs.cc:1015
      #16 0x00007f15758ede9a in start_thread (arg=0x7f1565ef4700) at pthread_create.c:308
      #17 0x00007f1574be1cbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112

      Trying to get some variables.
      Some pointers may be invalid and cause the dump to abort.
      Query (0x7f51240031d8): select * from t28953
      Connection ID (thread ID): 10
      Status: NOT_KILLED

      It's a race condition repeatable with some probability by running test rpl.rpl_events with query cache enabled:

      perl ./mtr rpl.rpl_events --mysqld=--query-cache-size=1048576 --mysqld=--binlog-format=row --repeat=20

      On my machine 3..5 attempts is usually enough to hit the failure.

      bzr version-info

      revision-id: sergii@pisem.net-20130513141139-vl0ehunm2bwgx1s9
      revno: 3764
      branch-nick: 5.5

      1202:    if (header->result() == 0)
      1203:    {
      1204:      DBUG_PRINT("error", ("End of data with no result blocks; "
      1205:                           "Query '%s' removed from cache.", header->query()));
      1206:      /*
      1207:        Extra safety: empty result should not happen in the normal call
      1208:        to this function. In the release version that query should be ignored
      1209:        and removed from QC.
      1210:      */
      1211:      DBUG_ASSERT(0);
      1212:      free_query(query_block);
      1213:      unlock();
      1214:      DBUG_VOID_RETURN;
      1215:    }




            sanja Oleksandr Byelkin
            elenst Elena Stepanova
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