Complex code in AsyncTask freeze progressBar - android-asynctask

I have a complex code in AsyncTask, which makes alot of I / O on SQLite and heavy calculation. This piece of code is very long and that's why I did not copy it here. When my code is commented AsyncTask works very well and update progress bar correctly, but with my code, the progress bar is frozen until at the end of my code.
Can anyone give me recommendations to respect, to write the program like mine with of course, a worker thread and a progress bar that works well?
I finished my project. in phase of development, I had no problem. but in phase testing with real data I am confronted with this problem. It's been three days that I read on a AsyncTask discussed on this forum but neither my help and I do not know what to do. I also frozen.
Thank you for your help.

The problem is resolved.
Apparently my code uses alot of CPU time and does not leave enough time for UIThread to update the screen.
So I set the portion of code that accede SQLite in another thread using a Handler and a CountDownLatch with 10ms delay to start the thread. and this delay allows android has to release time for UIThread to refresh. this way, publishProgress started working. Now I wonder if it's a good solution.

Related

xCode 9: Is it possible to switch off animation of xCode itself

just started with xCode 9.0 and I got the feeling, that all this "nice and beautiful" animations where hints and messages moved ANIMATED in and out during editing are ... painful...
I know it's a matter of taste, however, does someone know if it is possible to switch off these animations? .. and how and where?
EDIT: As someone casted this down (without explanation), maybe an explanation from me for the reasons of that question would be useful.
Maybe I'm doing it the wrong way, but when I code I have a rough idea in my mind, write some comments to sketch the idea and start coding. Coding is an interactive process where I type very fast, think, erase and retype etc. I also copy code fragments and "repair" it on its final destination etc.. highly interactive.
Xcode needs (on big code files) roughly a second to make decisions about giving the user a hint or not. Most annoying hint in the case I'm talking here is "missing blabla ..."
When start typing an statement it is of course not finished. The sad thing: by the time Xcode has done its decision process and end the animation to roll in the hint message (1 sec decision, 1 sec animation) the statement is already completed by me.
In fact, it is often done BEFORE the animation starts - but that is another story.
Luckily during the animation of rolling in (1 sec), Xcode find out that the hint is not needed anymore (decision time of 1 sec matches the animation happening in parallel) and rolls the hint back (animation duration 1 sec).
So all time I code there is a nice "firework" of outdated hint messages rolling in and out.
Don't get me wrong I love the hint messages and all the other messages which Xcode really helps to avoid hard to find code errors.
I simply do not like this animations, as they use one wasted second every time they appear. This is a nice feature for presentations (e.g. WWDC talks), but in day by day fast coding mode, they are not useful.
So I look for a way to switch just the animation off.
Thanks a lot in advance
Hardy

JDialog dispose and repainting problem

In a jnlp application, we create a modal popup extends from javax.swing.JDialog, and call dispose() to hide the dialog whenever necessary. However, sometimes the final client get repainting problem. The dialog doesn't really disappear, and its parent window look messy. I couldn't reproduce, but it happen many times on final client PC. I guess there are 2 possible reasons:
There is a thread in our application update the cursor directly. However, I can't prove this thread is the root cause of the issue.
Periodically, we have another process highly use the CPU in a few seconds. I tried to load the CPU, but I couldn't reproduce the issue too.
Any advice for me in this case?
Thanks!
It looks the answer is in the question ;-)
Having a thread (not the EDT) updating the UI (the cursor in your case) may lead to this kind of problem.
Hence, ensure that your thread calls SwingUtilities.invokeLater() (or invokeAndWait() depending on your needs).
Another possibility (but this depends a lot on what your thread does, without further description from your side, it is hard to tell) would be to use SwingWorker instead of a thread.

Total system freezing when using timers in graphical application

I’m really stuck with this issue and will greatly appreciate any advice.
The problem:
Some of our users complain about total system “freezing” when using our product. No matter how we tried, we couldn’t reproduce it in any of systems available for troubleshooting.
The product:
Physically, it’s a 32bit/64bit DLL. The product has a self-refreshing GUI, which draws a realtime spectrogram of an audio signal
Problem details:
What I managed to collect from a number of fragmentary reports makes the following picture:
When GIU is opened, sometimes immediately, sometimes after a few minutes of GIU being visible, the system completely stalls, without possibility to operate with windows, start Task Manager etc. No reactions on keyboard, no mouse cursor seen (or it’s seen but is not responsibe to mouse movements – this I do not know). The user has to hard-reset the system in order to reboot. What is important, I think, is that (in some cases) for some time the GIU is responsive and shows some adequate pictures. Then this freezing happens. One of the reports tells that once the system was frozen, the audio continued to be rendered – i.e. heard by the reporter (but the whole graphic shell of Windows was already frozen). Note: in this sort of apps it’s usually a specialized thread which is responsible for sound processing.
The freezing is more or less confirmed to happen for 2 users on Windows7 x64 using both 32 and 64 bit versions of the DLL, never heard of any other OSs mentioned with connection to this freezing (though there was 1 report without any OS specified).
That’s all that I managed to collect.
The architecture / suspicions:
I strongly suspect that it’s the GUI refreshing cycle that is a culprit.
Basically, it works like this:
There is a timer that triggers callbacks at a frame rate of approx 25 fps.
In this callback audio analysis is performed and GUI updated
Some details about the timer:
It’s based on this call:
CreateTimerQueueTimer(&m_timerHandle, NULL, xPlatformTimerCallbackWrapper,
this, m_firstExpInterval, m_period, WT_EXECUTEINTIMERTHREAD);
We create a timer and m_timerHandle is called periodically.
Some details about the GUI refreshing:
It works like this:
HDC hdc = GetDC (hwnd);
// Some drawing
ReleaseDC(hwnd,hdc);
My intuition tells me that this CreateTimeQueueTimer might be not the right decision. The reference page tells that in case of using WT_EXECUTEINTIMERTHREAD:
The callback function is invoked by the timer thread itself. This flag
should be used only for short tasks or
it could affect other timer
operations. The callback function is
queued as an APC. It should not
perform alertable wait operations.
I don’t remember why this WT_EXECUTEINTIMERTHREAD option was chosen actually, now WT_EXECUTEDEFAULT seems equally suitable for me.
In fact, I don’t see any major difference in using any of the options mentioned in the reference page.
Questions:
Is anything of what was told give anyone any clue on what might be wrong?
Have you faced similar problems, what was the reason?
Thanks for any info!
==========================================
Update: 2010-02-20
Unfortunatelly, the advise given here (which I could check so far) didn't help, namelly:
changing to WT_EXECUTEDEFAULT in CreateTimerQueueTimer(&m_timerHandle,NULL,xPlatformTimerCallbackWrapper,this,m_firstExpInterval,m_period, WT_EXECUTEDEFAULT);
the reenterability guard was already there
I havent' yet checked if updateding the GUI in WM_PAINT hander helps or not
Thanks for the hints anyway.
Now, I've been playing with this for a while, also got a real W7 intallation (I used to use the virtual one) and it seems that the problem can be narrowed down.
On my installation, using of the app really get the GUI far less responsive, although I couldn't manage to reproduce a total system freezing as someone reported.
My assumption now is this responsiveness degradation and reported total freezing have a common origin.
Then I did some primitive profiling and found that at least one of the culprits is BitBlt function that is called approx 50 times a second
BitBlt ((HDC)pContext->getSystemContext (), // hdcDest
destRect.left + pContext->offset.h,
destRect.top + pContext->offset.v,
destRect.right - destRect.left,
destRect.bottom - destRect.top,
(HDC)pSystemContext,
srcOffset.h,
srcOffset.v,
SRCCOPY);
The regions being copied are not really large (approx. 400x200 pixels). It is used for displaying the backbuffer and is executed in the timer callback.
If I comment out this BitBlt call, the problem seems to disappear (at least partly).
On the same machine running WinXP everything works just fine.
Any ideas on this?
Most likely what's happening is that your timer callback is taking more than 25 ms to execute. Then another timer tick comes along and it starts processing, too. And so on, and pretty soon you have a whole bunch of threads sucking down CPU cycles, all trying to do your audio analysis and in short order the system is so busy doing thread context switches that no real work gets done. And all the while, more and more timer ticks are getting placed into the queue.
I would strongly suggest that you use WT_EXECUTEDEFAULT here, rather than WT_EXECUTEINTIMERTHREAD. Also, you need to prevent overlapping timer callbacks. There are several ways to do that.
You can use a critical section in your timer callback. When the callback is triggered it calls TryEnterEnterCriticalSection and if not successful, just returns without doing anything.
You can do something similar using a volatile variable and InterlockedCompareExchange.
Or, you can change your timer to be a one-shot (WT_EXECUTEONLYONCE), and then re-set the timer at the end of every callback. That would make the thing execute 25 ms after the last one completed.
Which you choose is up to you. If your analysis often takes longer than 25 ms but not more than 35 ms, then you'll probably get a smoother update rate using WT_EXECUTEONLYONCE. If it's rare that analysis takes more than 25 ms, or if it often takes more than about 35 ms (but less than 50 ms), then you're probably better off using one of the other techniques.
Of course, if it often takes longer than 25 ms, then you probably want to increase the time (reduce the update rate).
Also, as one of the commenters pointed out, it's possible that the problem also involves accessing the GUI from the timer thread. You should do all of your analysis in the timer thread, store the results somewhere that the main thread can access it, and then send a message to the window proc, telling it to update the display.
Have you asked the users to disable Aero/WDMDWM? With Aero enabled, rendering is implemented quite different. Without Aero, the behaviour will be similar to XP. Not that it solves anything, but it will give you a clue as to what the problem is.

axapta thread / animation

i have a function which costs plenty of time.
this function is an sql-query called via odbc - not written in x++, since the functional range is insufficient.
while this operation is running, I want to show an animation on a form - defined in the aviFiles-macro.
trying to realize, several problems occur:
the animation doesn't start prior the function has finished.
using threads won't fulfill my hopes, since the odbc-settings are made on the server and i guess, the function is called on client-side.
besides - how am i able to get the information that the treaded task has ended up?
could anyone give me a hint, how to
play an animation on a form
do something ( in background ) and go on playing the animation until the task to perform is finished
stop the animation
coding this in exactly this order shows the behaviour mentioned above.
thanks in advance for hints and help!
You can use standard AotFind as an example:
split the work in small pieces each
piece should be executed at timer
tick
Also, you can try not to use timer, but to call infolog.yield() as often as possible.
this could potentially be done in a very complicated way with call backs and delegates if your odbc is in a vs project...
but isn't the real solution to try to find a faster/more effective way to query your data?

Is there any reason to retain a scheduled NSTimer if you don't need to invalidate it?

I'm going back over some crufty code to tidy it up and I see I've been retaining NSTimers returned from scheduledTimerWithTimeInterval:target:selector:userInfo:repeats: and storing them in a field - then releasing and nulling the field when it fires. In some cases I use the timer to send an invalidate message to it later - but in many cases not.
In more recent code I usually just schedule the timer and forget about it. I understand that the constructor method is autoreleasing and the timer is retained by the run loop while it is active - so I don't see any issue with this.
So, just to round out my understanding - is there any other reason I should be holding on to my timers, or is what I am doing now the accepted idiom?
This is all in the context of iPhone code, but I don't believe this is iPhone specific.
I just let the run loop handle the retention, myself - it's the run loop that owns the timer and not me. If you see what I mean.
I'm answering my own question.
I was mostly asking the question because I'd been browsing through the class reference docs and this issue was not really made clear. I've since read the Timer Programming Topics: Using Timers article in the ADC and it covers it pretty well - especially the section on memory management at the end.
According to that what I am doing now (just scheduling, unless I need to be able to call invalidate, or isValid etc) is the right way.

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