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21.5.14.43 The ndbinfo threadstat Table

The threadstat table provides a rough snapshot of statistics for threads running in the NDB kernel.

The threadstat table contains the following columns:

  • node_id

    Node ID

  • thr_no

    Thread ID

  • thr_nm

    Thread name

  • c_loop

    Number of loops in main loop

  • c_exec

    Number of signals executed

  • c_wait

    Number of times waiting for additional input

  • c_l_sent_prioa

    Number of priority A signals sent to own node

  • c_l_sent_priob

    Number of priority B signals sent to own node

  • c_r_sent_prioa

    Number of priority A signals sent to remote node

  • c_r_sent_priob

    Number of priority B signals sent to remote node

  • os_tid

    OS thread ID

  • os_now

    OS time (ms)

  • os_ru_utime

    OS user CPU time (µs)

  • os_ru_stime

    OS system CPU time (µs)

  • os_ru_minflt

    OS page reclaims (soft page faults)

  • os_ru_majflt

    OS page faults (hard page faults)

  • os_ru_nvcsw

    OS voluntary context switches

  • os_ru_nivcsw

    OS involuntary context switches

Notes

os_time uses the system gettimeofday() call.

The values of the os_ru_utime, os_ru_stime, os_ru_minflt, os_ru_majflt, os_ru_nvcsw, and os_ru_nivcsw columns are obtained using the system getrusage() call, or the equivalent.

Since this table contains counts taken at a given point in time, for best results it is necessary to query this table periodically and store the results in an intermediate table or tables. The MySQL Server's Event Scheduler can be employed to automate such monitoring. For more information, see Section 23.4, “Using the Event Scheduler”.