The error message is saying '... cannot access the file because it is being used by another process' which would indicate that something else is holding a lock onto the file and GeoEvent Processor cannot open it. Can you please ensure that you do not have the file open in Excel or another program and retry and let us know if this corrects the situation?
Thanks, Adam Mollenkopf ArcGIS GeoEvent Processor for Server - Product Lead
Yeah Adam, i can ensure that there isn't other process is taking the csv file when GEP is trying to take it. The ETL writes the file in a folder and then the same ETL moves the file to the GEP Folder. That move takes milliseconds.
Meanwhile, i solved the problem making a batch file (that works in the same GEP server trought a scheduled task) that moves the CSV file from folder where ETL writes the file to the GEP Folder. Since then all files have been taked from GEP without problems.
Adam, my other question is: What is the rate of read the files of GEP?