[MonoTouch] Did Threading change a lot in 5.2.latest?

[Nic Wise]

Hi there

I'm having a few issues in the newest versions of MT, mostly around
Threading (ok, ALL around threading).

this one is a fairly major, but easy to work around, one for me:

https://bugzilla.xamarin.com/show_bug.cgi?id=3676

I'm getting it when I use NewtonSoft Json.net from a thread. I worked
around it by using it from the UI thread, and caching the resulting
object (not a big deal at all in this case). The DLL I'm using hasn't
changed for a long time.....



However, I'm also having an issue with TestFlight's logging. If I log
in a thread, sometimes, I get a segfault. Not every time, but always
in the same place, and ALWAYS in a thread. The thread code is like
this:

Task.Factory.StartNew(() => {
                                CalculateSummary ();
                        }).ContinueWith(t => {
                                if (oncomplete != null) oncomplete();
                        }, new UIKitScheduler());

(UIKitScheduler is this: https://gist.github.com/1431457 )
CalculateSummary loads a bunch of stuff from SQLite, then the last line is:

Util.Log ("recalculating took {0}ms".Fmt (sw.ElapsedMilliseconds));

It is possible that the oncomplete is throwing an error, which I need
to check out - I've had issues with threading disappearing if the
continue throws an uncaught exception.

Anywho, Util.Log does a Debug.WriteLine (or Console.WriteLine, same
result), and a TestFlight.Log. The first works always. The latter
crashes _sometimes_, usually if he app is busy - ie, I'm moving
between screens (which triggers calculations) etc. But sometimes just
if it's sitting idle. I've tried putting the logging into a
InvokeOnMainThread, but with the same result.

I wasn't using TF before, but I've not had the Json problem in
previous versions (I have a lot of production code out there which is
working doing this). That said, I wasn't using Tasks before (I was
using the threadpool), which may also be it!

Any ideas? did this change after 5.2.4 (I'm on 5.2.8 I think at the moment)

I have a semi-stacktrace thing, but it has almost no actual info in
it. I'm going to try a debug build tonight, and see if I can get more
info out. console just shows that the app segfaulted (error 11 I
think??)

 Outside of that, everything is exceptionally delicious with iOS5, the
appearance API's, and the Task API's :)

N

-- 
Nic Wise
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