title: MySQL crashed with un-answered memory issue
body: <p>My website (Wordpress) sometimes stopped working with message &quot;cannot connect to Datatabse&quot;.</p>
  <p>I checked the log file of MySQL and I found the following crash-info:</p>
  <pre><code>---------- 
  2021-01-21  0:44:59 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
  2021-01-21  0:44:59 0 [Note] InnoDB: Uses event mutexes
  2021-01-21  0:44:59 0 [Note] InnoDB: Compressed tables use zlib 1.2.11
  2021-01-21  0:44:59 0 [Note] InnoDB: Number of pools: 1
  2021-01-21  0:45:00 0 [Note] InnoDB: Using SSE2 crc32 instructions
  2021-01-21  0:45:00 0 [Note] InnoDB: Initializing buffer pool, total size = 16M, instances = 1, chunk size = 16M
  2021-01-21  0:45:00 0 [Note] InnoDB: Completed initialization of buffer pool
  2021-01-21  0:45:00 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
  2021-01-21  0:45:00 0 [Note] InnoDB: Starting crash recovery from checkpoint LSN=215993122
  2021-01-21  0:45:07 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
  2021-01-21  0:45:07 0 [Note] InnoDB: Uses event mutexes
  2021-01-21  0:45:07 0 [Note] InnoDB: Compressed tables use zlib 1.2.11
  2021-01-21  0:45:07 0 [Note] InnoDB: Number of pools: 1
  2021-01-21  0:45:07 0 [Note] InnoDB: Using SSE2 crc32 instructions
  2021-01-21  0:45:07 0 [Note] InnoDB: Initializing buffer pool, total size = 16M, instances = 1, chunk size = 16M
  2021-01-21  0:45:07 0 [Note] InnoDB: Completed initialization of buffer pool
  2021-01-21  0:45:07 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
  2021-01-21  0:45:07 0 [Note] InnoDB: Starting crash recovery from checkpoint LSN=215993122
  2021-01-21  0:50:02 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
  2021-01-21  0:50:02 0 [Note] InnoDB: Uses event mutexes
  2021-01-21  0:50:02 0 [Note] InnoDB: Compressed tables use zlib 1.2.11
  2021-01-21  0:50:02 0 [Note] InnoDB: Number of pools: 1
  2021-01-21  0:50:02 0 [Note] InnoDB: Using SSE2 crc32 instructions
  2021-01-21  0:50:02 0 [Note] InnoDB: Initializing buffer pool, total size = 16M, instances = 1, chunk size = 16M
  2021-01-21  0:50:02 0 [Note] InnoDB: Completed initialization of buffer pool
  2021-01-21  0:50:02 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
  2021-01-21  0:50:02 0 [Note] InnoDB: Starting crash recovery from checkpoint LSN=215993122
  2021-01-21  0:50:02 0 [Note] InnoDB: 128 out of 128 rollback segments are active.
  2021-01-21  0:50:02 0 [Note] InnoDB: Removed temporary tablespace data file: &quot;ibtmp1&quot;
  2021-01-21  0:50:02 0 [Note] InnoDB: Creating shared tablespace for temporary tables
  2021-01-21  0:50:02 0 [Note] InnoDB: Setting file '/opt/lampp/var/mysql/ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
  2021-01-21  0:50:02 0 [Note] InnoDB: File '/opt/lampp/var/mysql/ibtmp1' size is now 12 MB.
  2021-01-21  0:50:02 0 [Note] InnoDB: Waiting for purge to start
  2021-01-21  0:50:02 0 [Note] InnoDB: 10.4.11 started; log sequence number 215993131; transaction id 221150
  2021-01-21  0:50:02 0 [Note] Plugin 'FEEDBACK' is disabled.
  2021-01-21  0:50:02 0 [Note] InnoDB: Loading buffer pool(s) from /opt/lampp/var/mysql/ib_buffer_pool
  2021-01-21  0:50:02 0 [Note] Server socket created on IP: '::'.
  ---------- 
  </code></pre>
  <p>I restarted MySQL and my website worked well.
  The version of my MySQL is: Distrib 10.4.11-MariaDB, for Linux (x86_64)
  Ubuntu version 20.</p>
  <p>This situation appeared a few times in the last month.</p>
  <p>I searched the solution in some posts before.</p>
  <p>I've already tried this configuration:</p>
  <pre><code>max_connections = 100  
  key_buffer = 50M
  max_allowed_packet = 10M
  thread_stack = 128K
  table_cache = 50
  </code></pre>
  <p>but it still downed.</p>
  <p>This is one source I've already found about my problem:
  <a href="https://stackoverflow.com/questions/19282583/mysql-keeps-crashing/20570269">MySQL keeps crashing</a></p>
  <p>Does anyone encountered the same issue, and knows a fix?</p>