Blocked source

Does the blocked state of a source have any affects to the inter arrival time:

Example with an easy model:

source=>processor=>sink

the processor has a constant process time of 20min.

The source has a normal distributed inter arrival time with mean = 20min and sd = 10min.

If the source creates a flowitem 10min before the finish of the ongoing process, this flowitem is blocked (because no queue is buffering it).

But if the random stream generator wants to create the next flowitem just 5 min after (possible because of the sd of the inter arrival time), it even cannot be created because there is already one created flowitem in the source which is blocked (in a kind of "source queue" with a maxcontent of one flowitem).

What happens if the "source queue" releases the blocked flowitem after another 5min (recent process is finished, released flowitem starts new process)?

• Will the inter arrival time to the next flowitem be calcutated from "zero" again, so that the next flowitem will be created after a "normal" calculated inter arrival time?
• Or will the flowitem which was about to create (but couldn't) be created immediately?
• Or will the flowitem which was about to create (but couldn't) be created after the "normal" inter arrival time calculated from "zero" minus the time it has been waiting for its "creation".
• Or if a created flowitem is waiting in the "source-queue", only inter arrival times longer than the time to finish of the ongoing process are generated. In this example at which a flowitem is created 10min before the end of the ongoing process and waiting in the "source-queue" only a inter arrival times longer than 10min will be calculated. But another question: Will the inter arrival time be adjusted (more shorter inter arrival times than the distribution originally allows if possible) because of some of these inter arrival times with minimum length?

Thanks a lot!

Congshi Wang

Yes, it's only STATE_GENERATING time that counts towards inter-arrival time. You can't alter this by changing the state, the time is sampled on reset and when the the flow-item exits.

The impact will be that you don't actually get an independent arrival distribution if the source is blocked, so you'll need another buffer to accept the items.

Thanks! I hope I've understood it correctly:

If a created flowitem is waiting in the "source-queue" (because the source is blocked), the inter arrival time to the next flowitem generation must be longer than the time to the finish of the ongoing process to ensure to have a non-blocked source.

No - I'd even speculate the opposite. To compensate for time in the blocked state, the inter-arrival time would need to be reduced to get back to the stated distribution.

The easiest way is to feed into a queue and then into your processor.