Re: Thread Shutdown

Hi Stuart,

> Hi, I am new to visad but am enjoying using it, except for a lack of
> understanding in the thread model.
>
> I am doing some offscreen image creation using DisplayImpl.getImage(true),
> have added data for a number of FlatFields.  The images come out great.
> I should point out that I am using the same DisplayImpls over and over for
> all images.  I'm using just 2D rendering.
>
> However, when I want to shutdown the visad part of my app, sometimes it
> hangs.  I'm doing this:
>
> displayImplA.destroy();
> displayImplB.destroy();
> ActionImpl.stopThreadPool();
>
> sometimes these three lines return OK.  Sometimes I get an exception
> mentioning a task queue (??) and sometimes it just hangs.  This is bad,
> since I run this job as a cron and the app must exit after it has done.
>
> Any help very gratefully appreciated.  I apologise of this is  FAQ, I
> couldn't locate it.  On  a broader note, how many threads should I expect
> if using two DisplayImpls.

Its not a FAQ - we've never seen this problem before.

We do need more information. Specifically, a stack dump with
line numbers for the Exception. And if you can get it to hang
while running under jdb, the output of 'where all' once it
hangs (as I recall, you need to run 'suspend all' before you
run 'where all').

Cheers,
Bill