[ImageJ-devel] ImageJ2 plugin thread question

[Yili Zhao]

Hi Curtis and Johannes,
  thanks for the "ThreadService" and "StatusService" tip, and I think
ImageJ2 developers have already considered this issue!

  By the way, it seems that there is a "event bus" framework in ImageJ2. I
just did a quick search, and found two "EventBus" frameworks: one is from
http://eventbus.org/, another one is from Google's Guava
https://code.google.com/p/guava-libraries/wiki/EventBusExplained.

  It seems that ImageJ2 uses EventBus from http://eventbus.org/, why?


2014-02-14 6:53 GMT+08:00 Curtis Rueden <ctrueden at wisc.edu>:

> Hi Yili,
>
> > will ImageJ2 run its plugin in a new thread?
>
> Yes, ImageJ2 launches plugins in their thread. See:
>
> http://jenkins.imagej.net/job/ImageJ-daily/javadoc/imagej/module/ModuleService.html#run(imagej.module.ModuleInfo,
> boolean, java.lang.Object...)
>
> ImageJ modules are typically fired using these run methods, which spawn a
> new thread using the ThreadService -- well, it's out of a ThreadPool, so in
> theory you could hit a limit if you run tons of modules at the same time.
>
> Note that the methods return a Future, so that you can block till
> execution is complete *if you want* but you are not forced to do so.
>
> > Suppose this plugin will perform a long time-consumed task
>
> If you write a command whose sole job is to perform some long-running
> task, just implement the task in the run method. You do not have to worry
> about threading unless you want the execution itself to be done using
> multiple threads. (In the future we plan to provide more transparent
> multi-threading, but right now modules execute on a single new thread.)
>
> > If this plugin need its own GUI, but this plugin is running in a
> > thread which is not the UI thread (event dispatch thread), and this
> > plugin's GUI should be created in UI thread for thread safe, how can
> > this be done?
>
> You do not need to create Swing UI component on the EDT. You can do it in
> any thread. It is only *after* you pack() and setVisible(true) that you
> need to be concerned about the EDT, and even then, if all you are doing is
> listening for GUI events (e.g., actionPerformed callbacks) then those
> already happen on the EDT so you don't need to worry.
>
> In short, in 99% of cases, you actually do not need to use
> EventQueue.invokeLater and similar. So even if you write an ImageJ command
> that spawns a Swing UI, you may not need this method.
>
> As Johannes says, if you want to stay general, look at the ImageJ
> ThreadService. It has UI-agnostic entry points into concepts like the EDT,
> without explicitly tying them to AWT/Swing in particular.
>
> > In the task running process, I want to report the running progress to
> > the ImageJ2 main frame
>
>
> http://jenkins.imagej.net/job/SciJava-common-javadoc/javadoc/org/scijava/app/StatusService.html
>
> The ImageJ UI (be it a Swing one, or other one) will take care of
> rendering your status messages and progress updates to the status bar or
> however it sees fit.
>
> Regards,
> Curtis
>
>
> On Thu, Feb 13, 2014 at 8:19 AM, Yili Zhao <panovr at gmail.com> wrote:
>
>> Hi,
>>   if I want to develop a plugin for ImageJ2, there are basically two
>> kinds of plugin:
>>
>>   1. first kind plugin does not need GUI;
>>
>>   2. second kind plugin does need GUI.
>>
>>   Suppose this plugin will perform a long time-consumed task, so I want
>> to ask that:
>>
>>   1. will ImageJ2 run its plugin in a new thread? Because in Swing
>> toolkit, all UI events should be processed in UI thread or the main thread,
>> and there is only One UI thread, so it is a single thread model.
>> Running a plugin in a new thread can guarantee the plugin will not block
>> ImageJ2's GUI.
>>
>>   2. If this plugin need its own GUI, but this plugin is running in a
>> thread which is not the UI thread (event dispatch thread), and this
>> plugin's GUI should be created in UI thread for thread safe, how can this
>> be done?
>>
>>   In order to avoid blocking the ImageJ2' user interface, I plan to do
>> like this:
>>
>>   1. execute the "long time-consumed task" in a separate worker thread;
>>
>>   2. In the task running process, I want to report the running progress
>> to the ImageJ2 main frame, so that the main frame can display a progress
>> information to let user know the current status;
>>
>>   3. When the task completed, it can notify the main frame, and the main
>> frame can response to this event.
>>
>>   How can I implement this asynchronous task model in ImageJ2? (I think
>> maybe I need some helper classes like  "SwingWorker" in JDK 6)
>>
>>   Thanks!
>>
>>
>> --
>> Yili Zhao
>>
>> _______________________________________________
>> ImageJ-devel mailing list
>> ImageJ-devel at imagej.net
>> http://imagej.net/mailman/listinfo/imagej-devel
>>
>>
>


-- 
Yili Zhao
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