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29.12.16.1 tp_connections 表

The tp_connections table contains one row per connection managed by the Thread Pool plugin. Each row provides information about the current state of a thread pool connection.

The tp_connections table contains the following rows:

  • CONNECTION_ID

    The connection ID as reported by SELECT CONNECTION_ID().

  • TP_GROUP_ID

    The index of the thread group in the global array. This column and TP_PROCESSING_THREAD_NUMBER serve as a foreign key into the tp_thread_state table.

  • TP_PROCESSING_THREAD_NUMBER

    This may be NULL if no thread is currently attached to the connection.

  • THREAD_ID

    The Performance Schema thread ID.

  • STATE

    The connection state; this is one of Established, Armed, Queued, Waiting for Credit, Attached, Expired, or Killed.

  • ACTIVE_FLAG

    When this is 0, the connection is not attached to any worker thread.

  • KILLED_STATE

    Reports the current stage in the process of killing the connection.

  • CLEANUP_STATE

    Reports the current stage in the cleanup process when closing the connection.

  • TIME_OF_LAST_EVENT_COMPLETION

    Timestamp showing when the connection last processed a request.

  • TIME_OF_EXPIRY

    Timestamp showing when an idle connection will expire if no new request arrives before then; this is NULL when the thread is currently processing a request.

  • TIME_OF_ADD

    Timestamp showing when the connection was added to the thread pool's connection request queue.

  • TIME_OF_POP

    Timestamp showing when the connection was dequeued (popped) from the queue by a connection handler thread.

  • TIME_OF_ARM

    Timestamp showing when the connection file descriptor was last added to the set monitored by poll() or epoll().

  • CONNECT_HANDLER_INDEX

    The index of the connection handler thread in the group which processed the connection request; a higher number means the connection load has triggered the creation of additional connection handler threads.

  • TYPE

    The connection type; this is one of User, Admin_interface or Admin_privilege; Admin_privilege means that this connection had been using the normal interface, but was placed in the admin group due to the user having the TP_CONNECTION_ADMIN privilege.

  • DIRECT_QUERY_EVENTS

    The number of queries executed directly by this connection.

  • QUEUED_QUERY_EVENTS

    The number of queued queries executed by this connection.

  • TIME_OF_EVENT_ARRIVAL

    A timestamp showing when poll_wait() returns with an event for the connection; this value is needed to calculate MANAGEMENT_TIME.

  • MANAGEMENT_TIME

    The accumulated time between the return from waiting on file descriptors; this includes the time spent queued for queries which are not executed directly.