21.6.15.43 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”.