AI Perception crash

Napoleonite · June 7, 2016, 11:04am

Code inside enemy in the constructor:

PerceptionComp = CreateDefaultSubobject<UAIPerceptionComponent>(TEXT("AIPerceptionComponent"));

SenseSightConfig = CreateDefaultSubobject<UAISenseConfig_Sight>(TEXT("SenseSightConfig"));
PerceptionComp->OnPerceptionUpdated.AddDynamic(this, &ABaseEnemy::OnSense);

PerceptionComp->SetDominantSense(SenseSightConfig->GetSenseImplementation());

SenseSightConfig->SightRadius = 9000.0f;
SenseSightConfig->LoseSightRadius = (SenseSightConfig->SightRadius + 20.0f);
SenseSightConfig->PeripheralVisionAngleDegrees = 90.0f;
SenseSightConfig->DetectionByAffiliation.bDetectEnemies = true;
SenseSightConfig->DetectionByAffiliation.bDetectNeutrals = false;
SenseSightConfig->DetectionByAffiliation.bDetectFriendlies = false;
PerceptionComp->ConfigureSense(*SenseSightConfig);

Sometimes when I duplicate an enemy with alt+mousedrag and 100% of the time when I press “EJECT” while playing in the PIE-editor will cause this crash:

Not being able to press “Eject” anymore just because I have AI Perceptions on my enemies is quiet bad and makes my debugging-life a lot harder.

From the 4.12 patch notes:

Bugfix: AI perception system stability
and performance improvements.

But it doesn’t say what stability fixes were exactly applied. I do not know if upgrading to 4.12 fixes any of the bugs I’m encountering. I prefer not to upgrade to 4.12 yet unless I really have to. Would be nice though if the patch notes would be a little bit more detailed. See also:

Sean_L · June 7, 2016, 2:59pm

Hello,

Could you please provide the logs from your project’s Saved->Logs folder after the crash occurs?

Could you please cause the crash to occur while not running in debug, and provide your Machine ID and ensure that you hit send on the Crash Reporter window (assuming you are getting a CR window)?

Thank you

Napoleonite · June 7, 2016, 4:33pm

The good news is (I do not know why): I can now eject again without the editor crashing, perhaps because of quite some changes between the last time I used eject and now.

The bad news is: I can no longer reproduce it and I do not seem to be able to track it down in the logs (it probably doesn’t even get logged). The only bug I found was this one everywhere: https://answers.unrealengine.com/questions/407113/how-can-i-fix-selection-16xpng-error.html but that one is fixed in 4.12.

And no there is no crash reporter window when crashing.

I’ll mark this as solved. If I encounter it again (hopefully not) then I’ll post it here with any possible crash logs & machine id.

Napoleonite · June 7, 2016, 10:08pm

Okay sadly this didn’t last long. I started a new clean 4.12.1 c++ FPS project. I was attempting to reproduce this bug: https://answers.unrealengine.com/questions/432086/ai-perception-bugs-when-simulating.html and then I actually reproduced this one instead, but only once.

However, there is no log of the crash. I checked the log (there was only one of course) and it only contained the usual stuff and there is nothing in the log regarding the crash.

The problem is still that this is not 100% reproducible and it’s pretty rare. In the last 24 hours only 3 of these crashes (2x in 4.11, once in 4.12). No crash reporter because I started it through VS :(. And I also failed to reproduce the other bug.

Napoleonite · June 9, 2016, 6:44pm

I managed to reproduce it in 4.12.1 100% of the time, but in my main project (because replicating it in a clean project takes a lot of time to setup).

Use AI Perception with some AI that can move.
Not sure if required but Behavior Tree(s) may also be required.
Start a playtest in PIE.
Use console command EnableGDT
Press Eject.
Crash:

You can see that the crash is caused by the engine and not by my code. But then again, AI perception imo is more unstable than most of the experimental features we have and should probably be marked experimental as well because it has a lot of bugs, has no documentation, is missing some features one would really need and even the internal code often not commented at all and only partially exposed to blueprints and you end up with workarounds. I use it for ~3 days, found 8 bugs, reported about 5 of them (lost count). Problem is that they are so hard to reproduce that I sometimes don’t even bother reporting them because I know there won’t be a bug report created anyway if you can’t recreate it in a clean project even though the bug is there.

I started the project without VS in order to get the crash debugger. I send the crash report and logs and here is my machine ID:
MachineId:E50BF435456046E23CBA09924D9E7371

Napoleonite · June 9, 2016, 6:50pm

My log from shortly before the crash (I believe it doesn’t log these kind of crashes):

[2016.06.09-18.38.58:605][601]Cmd:
EnableGDT
[2016.06.09-18.38.58:605][601]LogGameplayDebugger:Warning:
Got from client: EnableGDT
[2016.06.09-18.39.00:858][805]LogBlueprintUserMessages:
Early EndPlayMap Detection: Level
‘/Game/Maps/Debug.Debug:PersistentLevel’
has LevelScriptBlueprint
‘/Game/Maps/Debug.Debug:PersistentLevel.Debug’
with GeneratedClass
‘/Game/Maps/Debug.Debug_C’ with
ClassGeneratedBy
‘/Game/Maps/Debug.Debug:PersistentLevel.Debug’
[2016.06.09-18.39.01:004][805]LogBlueprintUserMessages:
Late EndPlayMap Detection: Level
‘/Game/Maps/Debug.Debug:PersistentLevel’
has LevelScriptBlueprint
‘/Game/Maps/Debug.Debug:PersistentLevel.Debug’
with GeneratedClass
‘/Game/Maps/Debug.Debug_C’ with
ClassGeneratedBy
‘/Game/Maps/Debug.Debug:PersistentLevel.Debug’
[2016.06.09-18.39.04:792][875]LogBlueprintUserMessages:
Early PlayInEditor Detection: Level
‘/Game/Maps/Debug.Debug:PersistentLevel’
has LevelScriptBlueprint
‘/Game/Maps/Debug.Debug:PersistentLevel.Debug’
with GeneratedClass
‘/Game/Maps/Debug.Debug_C’ with
ClassGeneratedBy
‘/Game/Maps/Debug.Debug:PersistentLevel.Debug’
[2016.06.09-18.39.04:795][875]LogPlayLevel:
PlayLevel: No blueprints needed
recompiling
[2016.06.09-18.39.04:795][875]PIE: New
page: PIE session:

Napoleonite · June 9, 2016, 6:56pm

Note that this is not the same crash as the original crash I had I believe. It crashed on a different part. So there may still be ANOTHER crash but I can not reproduce that one reliably.

Sean_L · June 9, 2016, 7:28pm

Hey Napoleon,

Thanks for coming back with additional information. I’ve followed the steps you’ve provided above, but it seems that I’m not mirroring your setup exactly, as I’m unable to get the issue to reproduce in a clean project on my end.

Here were the steps I followed:

Set up AI Perception on a Pawn
Used a Move To node to move the Pawn to my character when it was spotted
When the character moved, I entered the enablegdt command (also tried it with the ’ hotkey)
Then I pressed F8 to eject

After doing this, I did not experience a crash. Could you fill in the gaps in my repro steps to let me know what I may be missing to reproduce this on my end?

Although it can be time consuming, could you please reproduce this issue in a clean project and provide the repro steps, or a stripped-down test project that we can use to reproduce it on our end?

Napoleonite · June 9, 2016, 8:22pm

4.12.2 also has the bug.

I use shift+F1 and use the Eject button instead of F8 (because F8 doesn’t work for me (Inifile problem I guess)). I doubt that’s it though.

Also I changed my project > editor preferences > gameplay debugger and checked behavior tree, perception and gameview1 (over head & basic were already checked). However, unchecking those still crashes the editor 100% of the time so that’s not it either.

I also tried removing all AI from the level but it still crashes.

I fear that the real crash is caused by something else. I use a lot of AI perception so it may be a particular function/method or may not even be related to it, I do not know. I somewhat hope that the crash-report + machine id may provide a bit more info because I do not know how to reproduce this exactly in a clean project. It might be faster to copy my project and start disabling stuff until it works. But even that would take up quite a bit of time.

Here is the cause of the crash:

Also indeed I also can not reproduce it in a clean project. But knowing exactly where it crashed because of something being a nullptr shouldn’t be too hard to debug. This variable is only assigned to in 14 places total. And I’m not using a Hud (which also uses it). And I’m using a pre-compiled editor so it can hopefully not be my doing.

Sean_L · June 15, 2016, 7:05pm

Hey Napoleon,

I have been unable to reproduce this crash in a clean project on our end, and it appears that you have been unable to do so as well. If you do get repro steps, please feel free to reopen this thread, and we can continue to investigate this crash.

After speaking to our developers, they are currently working on updates for the Gameplay Debugger, which will most likely clean up any existing issues with the current code base.

Have a great day