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  1. MariaDB Server
  2. MDEV-29456

Spider hangs in 'Waiting for table metadata lock' state on CREATE TABLE after LOCK TABLES

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      Description

      This is a serious locking bug where Spider fails to see that table t was already created previously (and not locked?).
      Affects optimized and debug builds. Issue is not sporadic.

      INSTALL PLUGIN Spider SONAME 'ha_spider.so';
      CREATE USER Spider@localhost IDENTIFIED BY 'PWD123';
      CREATE SERVER srv FOREIGN DATA WRAPPER MYSQL OPTIONS (SOCKET '../socket.sock',DATABASE 'test',user 'Spider',PASSWORD 'PWD123');
      CREATE TABLE t (c INT) ENGINE=InnoDB;
      CREATE TABLE t1 (c INT) ENGINE=Spider;
      CREATE TABLE t2 (c INT) ENGINE=Spider COMMENT='WRAPPER "mysql",srv "srv",TABLE "t"';
      LOCK TABLES t2 WRITE;
      LOCK TABLES t1 READ;
      CREATE TABLE t (c INT) ENGINE=Spider;
      

      Leads to:

      10.11.0 bc563f1a4b0b38de3b41fd0f0d3d8b7f1aacbd8b (Optimized)

      10.11.0-dbg>LOCK TABLES t1 READ;
      ERROR 1429 (HY000): Unable to connect to foreign data source: localhost
      10.11.0-dbg>CREATE TABLE t(c INT) ENGINE=Spider;
      # Hang
      

      10.11.0 bc563f1a4b0b38de3b41fd0f0d3d8b7f1aacbd8b (Optimized)

      10.11.0-opt>SHOW FULL PROCESSLIST;
      +----+-------------+-----------+------+---------+------+----------------------------------------------------+-------------------------------------+----------+
      | Id | User        | Host      | db   | Command | Time | State                                              | Info                                | Progress |
      +----+-------------+-----------+------+---------+------+----------------------------------------------------+-------------------------------------+----------+
      |  5 | root        | localhost | test | Query   |   77 | Waiting for table metadata lock                    | CREATE TABLE t(c INT) ENGINE=Spider |    0.000 |
      |  6 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      |  7 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      |  8 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      |  9 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 10 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      | 11 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      | 12 | system user |           | NULL | Sleep   |   77 | Reset for next command                             | NULL                                |    0.000 |
      | 13 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      | 14 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 17 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 18 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 20 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 19 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 24 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 15 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 22 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      | 16 | system user |           | NULL | Daemon  | NULL | Spider table background cardinality action handler | NULL                                |    0.000 |
      | 21 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      | 23 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      | 25 | system user |           | NULL | Daemon  | NULL | Spider table background statistics action handler  | NULL                                |    0.000 |
      | 26 | spider      | localhost | test | Sleep   |   77 |                                                    | NULL                                |    0.000 |
      | 27 | root        | localhost | test | Query   |    0 | starting                                           | SHOW FULL PROCESSLIST               |    0.000 |
      +----+-------------+-----------+------+---------+------+----------------------------------------------------+-------------------------------------+----------+
      23 rows in set (0.001 sec)
      

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              Assignee:
              nayuta-yanagisawa Nayuta Yanagisawa
              Reporter:
              Roel Roel Van de Paar
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                Created:
                Updated:

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