Post-processor query fails from time to time



We have a problem with our Communications Server application in the Exstream 16.6.3 environment. We have created a project with Communications Builder which creates PDF documents based on the XMLIN-event and sends them to Document Broker Plus output connector to store certain documents (job output mode). We use auto-generated PPQ to query the documents from the DBR.

This works fine with our every other projects where DBR is used, but for some reason in this project we randomly get an error/warning message when trying to query the documents from the DBR:

"No document selected to be processed by Post-processor. Port:"

After the error the documents are in "waiting" state in the Document Broker database so they certainly are not missing. The query simply fails.

This happens randomly a few times in a year and it's very hard to reproduce in the developer environment but I've managed to do so.

This error happens when Communications Server application receives multiple files at the same time. The PDF creation phase works every time but PPQ input connector sometimes fails to query the files. I'm wondering if this has something to do with threading? Is it possible, that when the Communications Server application is processing + 10 files simultaneously, threads get somehow overlapped when trying to query the documents?

We are using input queues with default threading behavior. I've tried to delay the processing of the PPQ file to make sure documents are ready to process in the DBR but it makes no difference. I'm currently playing with "threadmanager.xml" to test if changing the default maxthreads values can have impact on this.

Is anyone else been having this same problem?