Selected Examples |
Another variant on batch service has the transactions
accumulating into a batch according to the arrival process and
has service scheduled as soon as the first transaction
arrives.
Service on the entire batch completes at once.
Figure 10.18: Batch Service
Figure 10.18 shows a model of this batch service.
When the first transaction arrives to the Server
labeled "Delay," it initiates the definition of a batch.
Any other transactions that arrive to that server are
discarded through the balk node.
When the delay is complete, the Trigger labeled
"Preempt Service" terminates service on all the transactions
in the MServer labeled "Batch Server."
As the transactions arrive, they accumulate in the MServer
for batch service. This server has a deterministic service
distribution with a large parameter value, for example, .
Note that because of the modeling technique used here, the
service time distribution is the minimum of and , an
exponential random variable.
If you want the service time distribution to be , then
use caution in choosing so that the probability that
is very small and highly unlikely to occur within
the number of samples planned.
Notice the LinePlot labeled "Server Utilization," which shows the number of transactions in service over time. It demonstrates graphically the accumulation of the batch and the dependent nature of the service completions.
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