I don't see why you're using a strong reference from the weak reference inside
your timer. You may be confusing ARC with that and your etc code. Change your
code to just use weakself rather than strongself when calling updateUI. If
there's a strong reference needed, try using self only. Also, is it possible
your function never ends? Check your etc code there.
--
Gary L. Wade (Sent from my iPhone)
http://www.garywade.com/
> On Sep 16, 2015, at 4:00 AM, Jean Suisse <jean.li...@gmail.com> wrote:
>
> Dear All,
>
> I have an app that uses Cocoa and dispatch sources leaking a lot (ca. 5GB /
> 17h). The origin seems to come from a combination of dispatch sources,
> Bindings & Core Animation. Below is a brief description of the app, what
> issues I encounter and the related code.
>
> DESCRIPTION OF THE APPLICATION
> I have a scientific data acquisition App that is expected to run continuously
> for a year and collect data every second from 144 sensors. The app is written
> in Objective-C, targets MAC OS, and uses GCD a lot. Basically, I start
> several dispatch queues running blocks to deal with scientific instruments
> connected to different data buses. I use appropriate synchronization tools or
> locking mechanisms to run everything safely and deal with concurrency.
>
> ISSUES
> At first, I did bind the 115 textfields (most having number formatters) on
> the main view directly to the properties of the class instances representing
> different physical scientific instruments. The issue was that it caused the
> UI being refreshed from various threads while my app was operating (timer
> dispatch sources manipulating the objects to collect data from instruments
> causing UI refresh through bindings). I got the message "CoreAnimation:
> warning, deleted thread with uncommitted CATransaction; set
> CA_DEBUG_TRANSACTIONS=1 in environment to log backtraces” a lot.
>
> So, I made a simple function (refreshUI) which transfers the data from
> non-bound properties of the objects to bound-properties of the objects like
> this :
>
>
> // [myInstrument updateUI];
> - (void)updateUI
> {
> assert([NSThread isMainThread]);
>
> // LEFT: property of the object tied to the UI through bindings made in IB
> // RIGHT: as a quick fix: variable member of the object updated using a
> background thread.
> self.lastPT100Temperature = self->l_PT100Temperature;
> self.lastPAAtmosphericPressure = self->l_PAAtmosphericPressure;
>
> // etc...
> }
>
> This function is called once every second on the main thread like this :
>
> - (void)startUIAutoUpdate
> {
> // @property (strong) dispatch_source_t uiRefreshTimer;
> self.uiRefreshTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER,
> 0, 0, dispatch_get_main_queue());
> dispatch_source_set_timer(self.uiRefreshTimer, DISPATCH_TIME_NOW, 1.0 *
> NSEC_PER_SEC, 0.25 * NSEC_PER_SEC);
>
> __weak typeof(self) weakself = self;
> dispatch_source_set_event_handler(self.uiRefreshTimer,
> ^{
> @autoreleasepool
> {
> __strong typeof(weakself) strongself = weakself;
>
> [strongself.myInstrument updateUI];
> // etc...
> }
> };
>
> dispatch_resume(self.uiRefreshTimer);
> }
>
> OBSERVATIONS
> The app starts by taking around 25 MB of memory (reported by Activity
> monitor). After 17h, I see around 5GB of memory used. After a few days… the
> app crashes. On the other hand, if I comment the family of lines
> "[strongself.myInstrument updateUI]", the app can run for a month using only
> 25-35 MB of memory. Data are still collected every second and stored on disk
> of course, but not shown on screen.
>
> If I prevent my app from trying to communicate with the instruments (by not
> instantiating the objects representing the communication interface) I can
> make it run faster and take thousands of dummy data points a second (and
> store them on the disk). The leaking issue is a little increased, but not by
> a factor of 1000. Only by a factor of 30 to 60. This is consistent with a UI
> refresh issue.
>
> Additionally, I was unable to find any leaks with Instruments (but I barely
> know how to use it) and the amount of memory reported by Instruments is far
> less than the one reported by Activity monitor (but still, the system starts
> swapping a lot after a while, so Activity monitor must be right). But
> interestingly, when switching apps with CMD-TAB, Instruments shows memory
> jumps (memory brutally decreases).
>
> QUESTION
> Well, I feel a little lost at this point. I lack the know-how to further
> investigate the issue. Does anyone know what to try / measure / observe to
> get more clues?
>
> Best Regards,
> Jean
> -----------
> Jean Suisse
> Institut de Chimie Moléculaire de l’Université de Bourgogne
> (ICMUB) — UMR 6302
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