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To monitor an application, the PATROL Agent must first discover the application and learn its current status. Discovery takes time and consumes system resources. To lessen the effect of discovery on system performance, the agent takes a snapshot of the system's process table and stores it in an internal memory structure referred to as the process cache.

When the agent runs a discovery script for an application, the script reads the information from the process cache. Because the cache is in memory, the process takes less time and uses less resources than querying the system. The cache is periodically updated at a user-defined interval. This update is referred to as the refresh. The first time an application discovery script runs after the process cache has been refreshed is called process cache update.

Note

It is possible to have both prediscovery and discovery PSL scripts running at the same time.

Relationship between cache and discovery

The getProcsCycles variable governs the rate at which the PATROL Agent Discovery Cache is refreshed. Each time the cache is refreshed, the agent runs a full application discovery. Any new applications and state changes are then displayed. The applCheckCycle variable determines how often the agent runs a partial application discovery between refreshes.

Process cache refresh rate

The /AgentSetup/AgentTuning/getProcsCycle configuration variable specifies the process cache refresh rate in seconds.

Format and type of data

Numeric, seconds

Default value

300

Minimum and maximum

20, none

Dependencies

/AgentSetup/AgentTuning/procCacheSched Priority

/AgentSetup/AgentTuning/procCachePriority

If either of these variables has a low priority, the cache refresh may be slightly delayed because other processes take priority in the OS or the agent. For example, the cache may be refreshed at intervals of 310 seconds, 305 seconds, or 300 seconds depending upon pending and running processes.

Recommendation

None

Application discovery rate

The /AgentSetup/AgentTuning/applCheckCycle configuration variable specifies the intervals at which the agent runs partial application discoveries.

Format and type of data

Numeric, seconds

Default value

40

Minimum and maximum

10, none

Dependencies

None

Recommendation

None


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