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  1. MariaDB Server
  2. MDEV-24433

Intentionally crash the server because it appears to be hung.

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      Following upgrade of our database from 10.2.8 to 10.5.6
      Our database started to crash every days
      [ERROR] [FATAL] InnoDB: Semaphore wait has lasted > 600 seconds. We intentionally crash the server because it appears to be hung.

      After investigation see below, we decided to add primary key on table and also temporary table => No crash for several days. Hope it continue.

      No change in our application
      In the log I found relevant information to investigate and try to workaround:

      Code involved:

      --Thread 139635575420672 has waited at dict0boot.ic line 37 for xxx seconds the semaphore:
      Mutex DICT_SYS created in dict0dict.cc:1032, lock var 2

      *Doing some research I found the occurence of this wait was caused by inserting a row in a inno table without primary key.
      *
      row_ins -> row_ins_alloc_row_id_step -> dict_sys_get_new_row_id

      See code row0ins.cc
      /**********************************************************//*
      Allocates a row id for row and inits the node->index field. */
      UNIV_INLINE
      void
      row_ins_alloc_row_id_step(
      /======================/
      ins_node_t* node) /*!< in: row insert node */
      {
      row_id_t row_id;

      ut_ad(node->state == INS_NODE_ALLOC_ROW_ID);

      if (dict_index_is_unique(dict_table_get_first_index(node->table)))

      { /* No row id is stored if the clustered index is unique */ return; }

      /* Fill in row id value to row */

      row_id = dict_sys_get_new_row_id();

      dict_sys_write_row_id(node->sys_buf, row_id);
      }

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            Unassigned Unassigned
            Rmekmouche Riad Mekmouche
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              Resolved:

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