Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-23065

Crash after setting wsrep_on to ON dynamically and reconnect

    XMLWordPrintable

    Details

    • Type: Bug
    • Status: Open (View Workflow)
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 10.3.22, 10.3.24
    • Fix Version/s: 10.3
    • Component/s: Galera, wsrep
    • Labels:
      None
    • Environment:
      Ubuntu 16.04

      Description

      Consider this .cnf file:

      openxs@ao756:~/dbs/maria10.3$ cat /home/openxs/galera/mynode1.cnf               [mysqld]
      datadir=/home/openxs/galera/node1
      port=3306
      socket=/tmp/mysql-node1.sock
      pid-file=/tmp/mysql-node1.pid
      log-error=/tmp/mysql-node1.err
      binlog_format=ROW
      innodb_autoinc_lock_mode=2
       
      wsrep_on=ON
      wsrep_provider=/home/openxs/galera/libgalera_smm.so
      wsrep_log_conflicts=ON
      wsrep_provider_options="cert.log_conflicts=YES"
      wsrep_cluster_name = singlebox
      wsrep_node_name = node1
      wsrep_cluster_address=gcomm://127.0.0.1:4567,127.0.0.1:5020,127.0.0.1:6020?pc.wait_prim=no
       
      log_bin
      log_slave_updates=1
      binlog_row_image=FULL
      gtid_domain_id=4100
      wsrep_gtid_domain_id=4100
      wsrep_gtid_mode=ON
      wsrep_restart_slave=1
      server_id=2
      slave-skip-errors=1062
      innodb_flush_log_at_trx_commit=2
      sync_binlog=0
      openxs@ao756:~/dbs/maria10.3$
      

      and server started with it but with wsrep_on set to OFF:

      openxs@ao756:~/dbs/maria10.3$ bin/mysqld_safe --defaults-file=/home/openxs/galera/mynode1.cnf --wsrep_on=OFF &
      [2] 20161
      openxs@ao756:~/dbs/maria10.3$ 200701 13:03:32 mysqld_safe Logging to '/tmp/mysql-node1.err'.
      200701 13:03:32 mysqld_safe Starting mysqld daemon with databases from /home/openxs/galera/node1
       
      openxs@ao756:~/dbs/maria10.3$ bin/mysql -uroot --socket=/tmp/mysql-node1.sock   Welcome to the MariaDB monitor.  Commands end with ; or \g.
      Your MariaDB connection id is 9
      Server version: 10.3.24-MariaDB-log Source distribution
       
      Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
       
      Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
       
      MariaDB [(none)]> show global status like 'wsrep_cluster%';
      +--------------------------+----------------------+
      | Variable_name            | Value                |
      +--------------------------+----------------------+
      | wsrep_cluster_conf_id    | 18446744073709551615 |
      | wsrep_cluster_size       | 0                    |
      | wsrep_cluster_state_uuid |                      |
      | wsrep_cluster_status     | Disconnected         |
      +--------------------------+----------------------+
      4 rows in set (0,002 sec)
       
      MariaDB [(none)]> set global wsrep_on = ON;
      Query OK, 0 rows affected (0,000 sec)
       
      MariaDB [(none)]> select 1;
      +---+
      | 1 |
      +---+
      | 1 |
      +---+
      1 row in set (0,000 sec)
       
      MariaDB [(none)]> \r
      Connection id:    10
      Current database: *** NONE ***
       
      MariaDB [(none)]> select 1;
      ERROR 2006 (HY000): MySQL server has gone away
      No connection. Trying to reconnect...
      ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql-node1.sock' (111)
      ERROR: Can't connect to the server
       
      unknown [(none)]> exit
      Bye
      

      As we can see, server crashes when we try to set wsrep_on to ON dynamically, after we reconnect to get new thread taking the value into account. In the error log we see:

      openxs@ao756:~/dbs/maria10.3$ tail -70 /tmp/mysql-node1.err                     2020-07-01 13:03:33 0 [Note] Added new Master_info '' to hash table
      2020-07-01 13:03:33 0 [Note] /home/openxs/dbs/maria10.3/bin/mysqld: ready for connections.
      Version: '10.3.24-MariaDB-log'  socket: '/tmp/mysql-node1.sock'  port: 3306  Source distribution
      200701 13:03:55 [ERROR] mysqld got signal 11 ;
      This could be because you hit a bug. It is also possible that this binary
      or one of the libraries it was linked against is corrupt, improperly built,
      or misconfigured. This error can also be caused by malfunctioning hardware.
       
      To report this bug, see https://mariadb.com/kb/en/reporting-bugs
       
      We will try our best to scrape up some info that will hopefully help
      diagnose the problem, but since we have already crashed,
      something is definitely wrong and this may fail.
       
      Server version: 10.3.24-MariaDB-log
      key_buffer_size=134217728
      read_buffer_size=131072
      max_used_connections=2
      max_threads=153
      thread_count=8
      It is possible that mysqld could use up to
      key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 467423 K  bytes of memory
      Hope that's ok; if not, decrease some variables in the equation.
       
      Thread pointer: 0x7fc678001098
      Attempting backtrace. You can use the following information to find out
      where mysqld died. If you see no messages after this, something went
      terribly wrong...
      stack_bottom = 0x7fc6c5949e98 thread_stack 0x49000
      /home/openxs/dbs/maria10.3/bin/mysqld(my_print_stacktrace+0x29)[0x55760af4cd29]
      mysys/stacktrace.c:270(my_print_stacktrace)[0x55760aa9c187]
      /lib/x86_64-linux-gnu/libpthread.so.0(+0x11390)[0x7fc6dd892390]
      sql/sql_connect.cc:1184(end_connection(THD*))[0x55760a9a3d59]
      sql/sql_connect.cc:1409(do_handle_one_connection(CONNECT*))[0x55760a9a45ca]
      sql/sql_connect.cc:1310(handle_one_connection)[0x55760a9a4764]
      /lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba)[0x7fc6dd8886ba]
      x86_64/clone.S:111(clone)[0x7fc6dcd1d41d]
       
      Trying to get some variables.
      Some pointers may be invalid and cause the dump to abort.
      Query (0x0):
      Connection ID (thread ID): 9
      Status: NOT_KILLED
       
      Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=on,condition_pushdown_for_derived=on,split_materialized=on
       
      The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
      information that should help you find out what is causing the crash.
      Writing a core file...
      Working directory at /home/openxs/galera/node1
      Resource Limits:
      Limit                     Soft Limit           Hard Limit           Units
      Max cpu time              unlimited            unlimited            seconds
      Max file size             unlimited            unlimited            bytes
      Max data size             unlimited            unlimited            bytes
      Max stack size            8388608              unlimited            bytes
      Max core file size        0                    unlimited            bytes
      Max resident set          unlimited            unlimited            bytes
      Max processes             14895                14895                processes
      Max open files            32184                32184                files
      Max locked memory         65536                65536                bytes
      Max address space         unlimited            unlimited            bytes
      Max file locks            unlimited            unlimited            locks
      Max pending signals       14895                14895                signals
      Max msgqueue size         819200               819200               bytes
      Max nice priority         0                    0
      Max realtime priority     0                    0
      Max realtime timeout      unlimited            unlimited            us
      Core pattern: |/usr/share/apport/apport %p %s %c %d %P %E
       
      openxs@ao756:~/dbs/maria10.3$
      

      So, something weird is going on when we try to execute any SQL after reconnection. To summarize:

      1. We have to prevent crash in this case.

      2. We should document that dynamic setting makes sense only if we started with wsrep_ON = ON.

        Attachments

          Activity

            People

            Assignee:
            jplindst Jan Lindström
            Reporter:
            valerii Valerii Kravchuk
            Votes:
            0 Vote for this issue
            Watchers:
            1 Start watching this issue

              Dates

              Created:
              Updated: