The ndbinfo threadstat Table

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

The following table provides information about the columns in the threadstat table. For each column, the table shows the name, data type, and a brief description. Additional information can be found in the notes following the table.

Column NameTypeDescription
node_idintegerNode ID
thr_nointegerThread ID
thr_nmstringThread name
c_loopstringNumber of loops in main loop
c_execstringNumber of signals executed
c_waitstringNumber of times waiting for additional input
c_l_sent_prioaintegerNumber of priority A signals sent to own node
c_l_sent_priobintegerNumber of priority B signals sent to own node
c_r_sent_prioaintegerNumber of priority A signals sent to remote node
c_r_sent_priobintegerNumber of priority B signals sent to remote node
os_tidintegerOS thread ID
os_nowintegerOS time (ms)
os_ru_utimeintegerOS user CPU time (µs)
os_ru_stimeintegerOS system CPU time (µs)
os_ru_minfltintegerOS page reclaims (soft page faults)
os_ru_majfltintegerOS page faults (hard page faults)
os_ru_nvcswintegerOS voluntary context switches
os_ru_nivcswintegerOS involuntary context switches

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 19.4, “Using the Event Scheduler”.

This table was added in MySQL Cluster NDB 7.1.17.