LibreOffice storeToUrl fails for large volume of docs

[zmotiwala]

Hello,
We are in the process of testing office conversion using Libre office 5.2.5 for a large volume of documents 20k plus.
The conversion process is using JOD as a wrapper around the libre office process.

I have maxTasksPerProcess set to 5000, but conversions start to fail rapidly and we get the following in the log file

by: com.sun.star.io.IOException: SfxBaseModel::impl_store <file://repo/pdf/<Unique_Identifier>/test.pdf> failed: 0x11b
at com.sun.star.lib.uno.environments.remote.Job.remoteUnoRequestRaisedException(Job.java:161) ~[jurt-5.2.5.jar:?]
at com.sun.star.lib.uno.environments.remote.Job.execute(Job.java:125) ~[jurt-5.2.5.jar:?]
at com.sun.star.lib.uno.environments.remote.JobQueue.enter(JobQueue.java:320) ~[jurt-5.2.5.jar:?]
at com.sun.star.lib.uno.environments.remote.JobQueue.enter(JobQueue.java:289) ~[jurt-5.2.5.jar:?]
at com.sun.star.lib.uno.environments.remote.JavaThreadPool.enter(JavaThreadPool.java:81) ~[jurt-5.2.5.jar:?]
at com.sun.star.lib.uno.bridges.java_remote.java_remote_bridge.sendRequest(java_remote_bridge.java:618) ~[jurt-5.2.5.jar:?]
at com.sun.star.lib.uno.bridges.java_remote.ProxyFactory$Handler.request(ProxyFactory.java:145) ~[jurt-5.2.5.jar:?]
at com.sun.star.lib.uno.bridges.java_remote.ProxyFactory$Handler.invoke(ProxyFactory.java:129) ~[jurt-5.2.5.jar:?]
at com.sun.proxy.$Proxy481.storeToURL(Unknown Source) ~[?:?

Since this is a test environment all files are named test.doc,test.docx, text.ppt etc i.e. they all start with test. My question is does storeToUrl fail because the file name test is the same i.e. test.pdf, the paths are all unique but does the office process use some temporary staging folder where we end up with file name conflicts?

Or am I getting the error because the volume is so large? We convert one file at a time , so all conversion happen serially. But once it fails it just fails for all .
Possible ideas on what could be going on?