Why get the attached system saturated?

[astrid_de_cock]

[ FlexSim 7.5.4 ]

astriddecock.fsm When running the program for a while (until 600 seconds or something), the whole system gets saturated and I don't understand why. So the source gives queue 2 different itemtypes, these itemtypes go to one of the sixteen processors, transported by a forklift. When the processing is done, the forklift brings the finished item back to queue 2. This runs well, until the moment the forklift reaches the last processor (21). Then he's just standing there, while there are finished items on the other processors.The whole system gets saturated: all the processors are having finished items but the forklift does not bring them to queue 2, but the strange thing is: no new itemtypes are coming on queue 2 as well. Can anyone explain / find out what's going wrong. Thank you very much.

[sam_stubbsYXX86 · Accepted solution]

The problem seems to be that your queue gets stuck. The processors are processing items slower than the items are arriving into the model, so the processors get filled up. But the processors send items back to the queue, so the queue gets into a deadlock. Because the new items coming in want the queue, and the items going out of the processor want the queue too.

My solution would be to create one queue for items coming into the model, and another queue next to it for items finished processing.

I've attached an example model below:

3818-astriddecock.fsm