UIMA-AS 2.4.0 - RunRemoteAsyncAE - destroy methods not called properly - JVM exits too early

[Elmar Haußmann]

Hello,

since we upgraded from UIMA-AS 2.3.1 to 2.4.0 we are having problems 
with the destroy methods of some components not being executed properly.
We are using the provided RunRemoteAsyncAE class with a collection 
reader (-c) and deploy an aggreate AE containing remotely scaled-out 
components. The aggregate AE has a co-located CAS Consumer at the end, 
which writes a single big ZIP file with all the results. The ZIP's 
OutputStream is closed in the destroy method. After upgrading to AS 
2.4.0 the destroy method is often not called at all or interrupted 
during execution resulting in corrupt ZIP files. I suspect it is because 
in RunRemoteAsyncAE.java:

private void stop() {
  try {
    uimaEEEngine.stop();
    } catch( Exception e) {
  }
  System.exit(1);
}

the call to uimaEEEngine.stop() is non-blocking and afterwards 
System.exit(1) directly quits the JVM, apparently interrupting proper 
clean-up. Waiting some time after calling uimaEEEngine.stop() or 
removing System.exit() completely results in proper cleanup, but is only 
a work-around.
Is this a bug? Is there a way to check whether the engine has stopped 
successfully or what is the suggested way to work around this? Also, I 
am wondering why this was never a problem in UIMA-AS 2.3.1 where this 
code is identical.

Thanks for any help!

Regards, Elmar