Probe Session Scheduling

Probe sessions are scheduled by the Tracked Object Manager's scheduler. The scheduler rate limits the number of sessions that run every second using the leaky bucket paradigm. The scheduler's current rate limit is 200 sessions per second.

The probe attributes control the operational mechanics of the scheduler. Each probe session takes several actions during the lifetime of a particular transaction. A probe session retrieving or releasing a system resource may cause a variation in its scheduling and it may also reduce the scheduler‘s rate limit for that second interval.

In addition, the scheduler's rate limiter dampens the Tracked Object Manager's CPU utilization during periods of heavy load, with the possible effect of delaying any number of the session's transactions.

Collecting packet timing information requires a constant transmit rate for the ICMP echo requests. The Tracked Object Manager supports this, but enforces a restriction on the receive wait value for ICMP timing probes. The receive wait value CANNOT be larger than the transmit interval. You configure the transmit interval and receive wait values in milliseconds for the timing probe, but the regular ICMP, UDP, and TCP probe attributes are configured in seconds.