Re: Thread Shutdown


There is something in the mail archive related to this. (

It seems that putting a delay between the destroys and the stopThreadPool() might help.


Bill Hibbard wrote:
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:


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').


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