Re: invokeLater and weird race conditions in my swing app

From:
Lew <lew@lewscanon.com>
Newsgroups:
comp.lang.java.help
Date:
Sun, 09 Sep 2007 20:22:05 -0400
Message-ID:
<BeOdnSyySYKzE3nbnZ2dnUVZ_u2mnZ2d@comcast.com>
apm35@student.open.ac.uk wrote:

Something like SwingWorker could be used to separate out the tasks of
GUI updates and non-GUI work. The non-GUI work would be done in
doInBackground in the usual way but the done method would write the
GUI command message to the queue that is read by GUIProcessor. Thus
the GUI-CB bit also gets its GUI work sent to the EDT via GUIProcessor
and also manages the non-GUI work in a simple way. In fact it could
all be bound in the doInBackground method, there would be need for
separation since the GUI calls are done via a queue. This also would
mean tha the GUI-CB would not have to worry about the swing single
threaded model.


Who reads the queue?

I'd say deviating from the wisdom is dangerous in Swing, but I'd be interested
in your results. As I stated, I'm totally not a guru on this, but I've been
studying this in /Java Concurrency in Practice/ and I'm thoroughly fascinated.

Your description of the use of SwingWorker sounds just like what Goetz
describes as a best practice in that book.

The advantage of SwingWorker is that it handles the thread dangers for you in
a more-or-less reliable way. If you combine it with one of the
java.util.concurrent.Executors as Goetz recommends it gets pretty easy.

The thing you are resisting is that Swing is an API - it's for you to use to
solve problems, not a solution to those problems for you. It is at a lower
level than what you are lamenting the lack of. That which you request is
pretty much provided, though, with SwingWorker and related idioms.

I know I sound unsympathetic, but as the Zen masters say, if you want to be
happy, when drawing water, draw water, when chopping wood, chop wood.

--
Lew

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