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21.5.10.43 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.

Table 21.393 Columns of the threadstat table

Column Name Type Description
node_id integer Node ID
thr_no integer Thread ID
thr_nm string Thread name
c_loop string Number of loops in main loop
c_exec string Number of signals executed
c_wait string Number of times waiting for additional input
c_l_sent_prioa integer Number of priority A signals sent to own node
c_l_sent_priob integer Number of priority B signals sent to own node
c_r_sent_prioa integer Number of priority A signals sent to remote node
c_r_sent_priob integer Number of priority B signals sent to remote node
os_tid integer OS thread ID
os_now integer OS time (ms)
os_ru_utime integer OS user CPU time (µs)
os_ru_stime integer OS system CPU time (µs)
os_ru_minflt integer OS page reclaims (soft page faults)
os_ru_majflt integer OS page faults (hard page faults)
os_ru_nvcsw integer OS voluntary context switches
os_ru_nivcsw integer OS 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 23.4, “Using the Event Scheduler”.


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