3.4.2 How to issue an event

The two ways of issuing an event include the frequency type and the incremental type, depending upon the monitoring target for which the threshold value is set. The following table describes the mapping of event issuing methods and monitoring targets.

Table 3‒23: Mapping of event issuing methods and monitoring targets
Event issuing method	Monitoring target
Frequency type	Number of Full GC occurrences
Incremental type	Number of entire pending requests for Web containers Number of pending requests for Web containers Number of entire pending requests for Web applications Number of pending requests for Web applications Number of pending requests for URL groups

Organization of this subsection

(1) For the number of Full GC occurrences (frequency type)
(2) In the case of number of pending requests in a URL group (incremental type)

(1) For the number of Full GC occurrences (frequency type)

The number of times Full GC occurs within a preset length of time (threshold watcher interval) is counted, and when the counter value reaches the threshold, an event is issued.

The following figure shows how a threshold event is issued for the number of Full GC occurrences.

Figure 3‒3: Issuing of an event of threshold value (for the number of Full GC occurrences)

In the preceding figure, the threshold for the number of Full GC occurrences is 10 and the threshold watcher interval is 5 minutes. From when the monitoring of operating information starts, the number of Full GC occurrences is counted in each threshold watcher interval. If the counter value in a threshold watcher interval exceeds the threshold (10), an event is issued.

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(2) In the case of number of pending requests in a URL group (incremental type)

Specify the maximum and minimum threshold values and issue an event when the number of pending requests in a URL group reaches the respective threshold value. The event of maximum threshold value and the event of minimum threshold value are issued at the timing mentioned below. The maximum threshold value needs to be greater than the minimum threshold value.

A maximum threshold value event is issued when the number of pending requests in a URL group reaches the maximum threshold value (warning zone).
A minimum threshold value event is issued to indicate that normal state is restored, when the number of pending requests in a URL group reaches the minimum threshold value after a maximum threshold value event was issued.
A maximum threshold value event is issued when the maximum threshold value is reached once again after the number of pending requests in a URL group has fallen below the minimum threshold value once after the maximum threshold value event was issued. A maximum threshold value event is not issued when the maximum threshold value is reached again without reaching the minimum threshold value, after the maximum threshold value event was issued.
A minimum threshold value event is issued when the minimum threshold value is reached again after the number of pending requests in a URL group exceeds the maximum threshold value since a minimum threshold value event was issued. A minimum threshold value event is not issued when the minimum threshold value is reached again without reaching the maximum threshold value, after the minimum threshold value event is issued.

The following figure illustrates the issuing of a threshold value event when the number of pending requests in a URL group is used:

Figure 3‒4: Issuing of a threshold value event (when the number of pending requests in a URL group is used)

In the above figure, a maximum threshold value event is issued when the threshold value reaches the maximum value from the normal zone. Next, the maximum threshold value is reached once again after falling below the maximum threshold value, but a maximum threshold value event is not issued at this time. From this point onwards, a minimum threshold value event is issued when the minimum threshold value is reached and a maximum threshold value event is issued when the maximum threshold value is reached.

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