App Crash on iPad

Trouble with Synthesia, your keyboard, or adapter? Think you found a bug?
When describing problems, always mention your OS and game version (shown at the bottom of the title screen).
  • If your keyboard has USB or MIDI ports, there is a tremendously high chance (>99%) it will work with Synthesia. See what you'll need on the keyboards page.
  • If you have a Logitech webcam and can't get your keyboard/adapter to work, see this post.
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Jixa
Posts: 19

Post by Jixa » 12-22-19 3:56 pm

This issue occurs both playing and perusing through the songs.
If you double tap on the song, then double tap to start practice, then realise the song is too hard so tap back, then tap songs.
Do this like 5~10 times in a row, the app crashes and all saved progressed is lost.

EDIT: v10.6.1.5337
Music Input = touchscreen keyboard 88key off and casio usb-midi 61key on
Music Output = off and off

Jixa
Posts: 19

Post by Jixa » 12-22-19 7:19 pm

I can replicate the hell out of this crash.
Open the app, do not even need a keyboard plugged in.
Open a song by double tapping,
then click back.
Do this enough times and the app crashes.
After an hour of playing, it seems to accumulate.

Nicholas
Posts: 12389

Post by Nicholas » 12-23-19 4:23 pm

This sounds like the same thing that's plaguing the latest Android build, too. :?

newCrashes.png
newCrashes.png (11.34 KiB) Viewed 4151 times

It's in the most inexplicable place. One of those things that should never be able to crash. Like... the code isn't even really doing anything at the point where it's having trouble. In any event, hopefully I'll be able to track this down in the next couple days. Sorry again for the inconvenience!

Jixa
Posts: 19

Post by Jixa » 12-26-19 10:09 pm

Thanks! Were you able to replicate? Need me to test a beta?
I’ve gone back to paper books until this issue is resolved, I mean the paper book can potentially fall over, that’s an analogue crash right?

Nicholas
Posts: 12389

Post by Nicholas » 12-27-19 1:49 am

Curiously, this is starting to look like one of those horrible bugs that programmers tell like ghost stories around the campfire: it doesn't seem to occur in "debug mode" (which is the way a programmer generally works 95% or more of the time) but it does in "release mode", where the compiler optimizes the code even further.

When the only difference between the bug occurring and not occurring is which of the (totally opaque) optimizations the compiler decided it might be able to employ on your source code, it can often be next to impossible to track down what's going on. The last time this happened (in 2012, while developing the more robust UI system for the not-yet-released iPad version), sometimes tapping a button (any button on any screen at about a 1% chance) would cause the app to crash. But only in release mode. My solution at the time was to simply turn off optimizations in Release mode until I eventually tore out the whole button event-notification handler code and rewrote it from the ground up.

Following the old advice, I started trying to track this down by spending a couple hours adding a small Lua scripting component to the app. (This is exactly the type of thing that Lua is for.) From there it only took five lines of script to tell the app to "exercise" itself: from the title screen press enter 3 times, then press escape 3 times. That makes it all the way into a song and all the way back out to the title screen. Then, I had it repeat that 50 times, fast enough that I could run the test in under two minutes.

No crash.

Trying each run of fifty attempts more than a dozen times now (in debug mode), still no crash. On any platform.

Then it was Christmas.

My next test will be in release mode. Then we'll see if it's compiler optimizations causing the trouble. The bad news is that tracking crashes down in release mode is usually about as easy as it is from the crash dumps I've already seen for this problem. :?

Nicholas
Posts: 12389

Post by Nicholas » 12-29-19 4:49 am

I think I found it. That means the hard part is probably over.

With any luck, we'll be able to submit an app update in a few days (presumably after Apple comes back from New Years).

Jixa
Posts: 19

Post by Jixa » 12-29-19 2:25 pm

Excellent news!
Triage, Development, Test, Deploy... the cycle continues :)

Jixa
Posts: 19

Post by Jixa » 01-11-20 4:01 pm

Issue persists :( More saved progress lost!
Cannot even find a good alternative to use whilst this issue exists.
Any update on progress for resolution

Nicholas
Posts: 12389

Post by Nicholas » 01-11-20 4:35 pm

I have a single, critical (crash/graphics corruption) item left that we're looking into before I click the "Release it to all platforms!" button. Sorry for the wait.

Jixa
Posts: 19

Post by Jixa » 01-13-20 5:46 am

Awesome news! As a User I would much prefer a stable and tested released over this rushed approach that seems to be trending and introducing more bugs... As a Human I am eager and keen, or in other words, impatient.
Appreciate the update! :)

Nicholas
Posts: 12389

Post by Nicholas » 01-14-20 2:29 pm

Found and "fixed" (for some definition of fixed). :lol:

Beginning the roll-out process now. This usually takes a day or two for iPad.

Maybe this 10.6 will be more stable than all the other 10.6's. :?

Nicholas
Posts: 12389

Post by Nicholas » 01-14-20 10:12 pm

Day or two, nothin'! Apparently 10.6.2 is already live in the App Store. Please let me know if this is fixed now. Thanks!

Jixa
Posts: 19

Post by Jixa » 01-19-20 2:52 pm

Hello, yes this issue appears to be resolved! I have almost finished easiest & easier... few more songs and I can move on to easy! Hasn’t crashed, has worked flawlessly! Good update :)
Thanks!

Nicholas
Posts: 12389

Post by Nicholas » 01-19-20 10:06 pm

That's great news! Thanks for the follow-up. :)

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