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”.