UDTF: PartitionWriter::next() call fails because of closed tcp connection

mproebstl

I created a User defined Transform Function in C++ on Vertica 10.1 and it crashes from time to time on a PartitionWriter::next() call with the exception: "Can't recv() in getWriteableBlock() Connection reset by peer"
I call it like this

outputWriter.setInt(0, value0);
outputWriter.setInt(1,value1);
outputWriter.next();

The vsql call gets the error message "[VJDBC] (8092) ERROR: Failure in UDx RPC call InvokeProcessPartition() in User Defined Object [Udx]: Message header check failed."
In the UDx log the message "Error in recv(): Vertica process has closed the socket" is shown.
I don't know why the socket is closed from time to time, especially since this only occurs from time to time and most of the time it works fine.
Did someone else have this or a similar problem?