UNO hanging or LibreOffice crashing

Hello,

I digged up an old project that was made for OpenOffice 3.3 back then. UNO used in Java, talking to swriter to create documents with virtually every possible content and save them as ODT, DOC, DOCX and PDF. This did work quite stable then, with Java 1.5 and 1.6, all in 32 bit and on Linux.

Now I updated. LibreOffice, I tried with 6.0.7, 6.1.5 or 6.2.2. Java is 1.8 from Oracle, still 32 bit, running on Linux and Windows. After having taken care of the UNO API changes in my code, I can create documents as before.

I can configure the application to work with one single UNO connection, used by one or multiple threads, or have a UNO connection per thread. LibreOffice is started like this:

--headless --nofirststartwizard --nologo --nodefault --norestore --nolockcheck --accept="socket,host=localhost,port=8100,tcpNoDelay=1;urp;"

However after the application has created a couple of documents, LibreOffice either crashes, printing out Application Error to standard out, or the UNO connection is hanging in JobQueue.removeJob() and my threads are locked.

Does anyone have an idea where I could look / ask for an answer to this? Did somebody else encounter similar problems using UNO ?

Thanks for any help,
Stephan