[android-developers] Re: how to get reference to GLSurfaceView's rendering thread?

Well I don't know if Java built a landmine into join() ;-) but in
C/C++ I have used phtread_join() many times (usually as part of an
idiom where you have a thread executing a "while (running) {}" loop
and another thread sets running=false and then join()s the other
thread to make sure it's gone), I've seen my coworkers use it and I
don't remember ever observing, or anybody mentioning anything dubious
about join() -so I'm curious, what's supposed to be the problem?

(Not that it matters to my original problem as the rendering thread
does not exit as part of onPause() handling...)

On Sat, Aug 4, 2012 at 2:49 AM, Indicator Veritatis <mej1960@yahoo.com> wrote:
> Of my two favorite books on concurrency in Java, one recommends never using
> join() in the first place, the other uses it only for a "poison-pill" in an
> implementation of producer-consumer when you know you want to shut it down
> if the queue ever empties completely.
>
> Now I realize it is not very helpful to say "don't do that" without offering
> a better alternative, but I see from the other responses that this is not a
> simple problem. The best I can do to help is say 1) as above, don't use
> 'join()', which is so rarely the right tool 2) don't wait until
> onDrawFrame() is called to load libraries. That is much too late in the
> process. Even waiting for onResume() might be too late. 3) the suggestion of
> using AsyncTask for loading libraries is good, but see Meike's talk about
> the 'gotchas' of using AsyncTask. It is at
> git://github.com/bmeike/OSCON.git.
>
> BTW: those two books are "Multithread Programming with Java Technology" by
> Berg et al, and "Java Concurrency in Practice" by Goetz.
>
>
> On Thursday, August 2, 2012 8:18:04 AM UTC-7, Latimerius wrote:
>>
>> I'd like to call join() on it to make sure the thread has exited.
>>
>> (Broader context for those interested: I have a crash in my GL-based
>> app that happens like this:
>>
>> - device is put to sleep with my app in the foreground
>> - an incoming call wakes the device up
>> - I receive onResume() and I call onResume() on my GLSurfaceView
>> - I receive onPause() almost immediately after onResume() since the
>> phone app goes to the background due to the incoming call
>> - the time between onResume() and onPause() is rather short but enough
>> for GLSurfaceView to go through all of its setup up to and including
>> the initial onDrawFrame() call
>> - my onDrawFrame() goes into texture & geometry loading routine which
>> can take up to several seconds so it's still loading when onPause() is
>> called as mentioned previously
>> - like many people here I have a globally-accessible method of
>> retrieving a reference to my main Activity to be used as the current
>> Context. This is used while loading graphics data to read asset
>> files.
>> - this Context reference however gets nulled out in onPause() in an
>> attempt not to leak main Activity instances. As the main thread
>> running onPause() nulls it while the rendering thread is still needing
>> it to finish loading the program crashes.
>>
>> The idea is to call GLSurfaceView.onPause() and then wait until the
>> rendering thread actually exit. Then null the Context reference.)

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