This method counts the frequency of full garbage collection occurring at each specified monitoring time (threshold value monitoring interval) and issues an event when the threshold value is reached.

The following figure illustrates the issuing of an event of threshold value when the frequency of full garbage collection is used:

Figure 3-3 Issuing of an event of threshold value (when the frequency of full garbage collection is used)

In the above figure, the threshold value of full garbage collection frequency is 10 and the threshold value monitoring interval is 5 minutes. The frequency of full garbage collection is counted at each threshold value monitoring interval, since the monitoring of statistics began, and an event is issued when the full garbage collection exceeds 10 times in a single threshold value monitoring interval.

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.