Crash in Unreal UJSBSimMovementComponent::DeInitializeJSBSim()

[baimengmengmeng]

This issue is due to a memory leak in the JSBSimMovementComponent.cpp file of jsbsim. The delete Exec; statement is causing a crash when the level is switched after packaging and exporting. Commenting out the delete Exec; statement resolves the issue?

void UJSBSimMovementComponent::DeInitializeJSBSim()
{
if (JSBSimInitialized)
{
UE_LOG(LogJSBSim, Display, TEXT("DeInitializeJSBSim"));

if (Exec)
{

  //delete Exec;
  Exec = nullptr;

  Atmosphere = nullptr;
  Winds = nullptr;
  FCS = nullptr;
  MassBalance = nullptr;
  Propulsion = nullptr;
  Aircraft = nullptr;
  Propagate = nullptr;
  Auxiliary = nullptr;
  Inertial = nullptr;
  Aerodynamics = nullptr;
  GroundReactions = nullptr;
  Accelerations = nullptr;
  IC = nullptr;
}

JSBSimInitialized = false;

}
}

I need to manually comment out delete Exec; to prevent the crash, but I suspect it may affect other issues, such as memory leaks.
My English is not good, please forgive me.

[baimengmengmeng]

In the editor, no matter how you switch levels, I use the open level blueprint function to switch levels, and it won't crash. As long as it is packaged and output as an EXE, running the switch level will crash. I found that if you comment out the delete Exec, it won't crash, but I'm afraid it will cause memory leaks. So, is there a problem with my usage or should I set something up?

[gallonmate]

You can move the Exec part to the bottom and everything seems to work. Like this:

if (Exec)
{

  Atmosphere = nullptr;
  Winds = nullptr;
  FCS = nullptr;
  MassBalance = nullptr;
  Propulsion = nullptr;
  Aircraft = nullptr;
  Propagate = nullptr;
  Auxiliary = nullptr;
  Inertial = nullptr;
  Aerodynamics = nullptr;
  GroundReactions = nullptr;
  Accelerations = nullptr;
  IC = nullptr;

  delete Exec;
  Exec = nullptr;
}

[baimengmengmeng]

Sorry my friend, according to your method, I packaged and output, but it still crashed. However, when I run it in the editor, it doesn't crash. Is this a bug?

[baimengmengmeng]

Thank you very much for answering my question, but it still crashes, and it starts to crash after being packaged into an independent program. There is no problem in the Unreal Editor.

[gallonmate]

If that doesn't work for you, here is a another solution. Change JSBSim simulation/jsbsim-debug to value of 0.

By default JSBSim is set to debug level 1, which causes it's internal logging system to log information when some classes are deconstructed. I don't know if it's incompatibility with how UE5 is using JSBSim or if it's JSBSim bug. Regardless, JSBSim debug level to 0 turns off the extra logging and there is no crash.

[karelkalata]

Add to TickComponent

if (!JSBSimInitialized || !Exec || !FCS) 
{
    return;
}

and try this out, I've also run into a crash

if (JSBSimInitialized)
{
   JSBSimInitialized = false;
   if (Exec)
   {
       Aircraft = nullptr;
       IC = nullptr;
       Propulsion = nullptr;
       MassBalance = nullptr;
       Propagate = nullptr;
       Auxiliary = nullptr;
       Aerodynamics = nullptr;
       Inertial = nullptr;
       FCS = nullptr;
       delete Exec;
       Exec = nullptr;
   }
}

[baimengmengmeng]

Thank you for responding, my friend, but unfortunately, following your method still results in a crash.

…

------------------ 原始邮件 ------------------ 发件人: "JSBSim-Team/jsbsim" ***@***.***>; 发送时间: 2025年10月10日(星期五) 中午1:33 ***@***.***>; ***@***.******@***.***>; 主题: Re: [JSBSim-Team/jsbsim] This issue is due to a memory leak in the JSBSimMovementComponent.cpp file of jsbsim. The delete Exec; statement is causing a crash when the level is switched after packaging and exporting. Commenting out the delete Exec; statement resolves the issue? (Discussion #1346) Add to TickComponent if (!JSBSimInitialized || !Exec || !FCS) { return; } and try this out, I've also run into a crash ` if (JSBSimInitialized) { JSBSimInitialized = false; if (Exec) { Aircraft = nullptr; IC = nullptr; Propulsion = nullptr; MassBalance = nullptr; Propagate = nullptr; Auxiliary = nullptr; Aerodynamics = nullptr; Inertial = nullptr; FCS = nullptr; delete Exec; Exec = nullptr; } }` — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.Message ID: ***@***.***>

[karelkalata]

One thing left to fix: everywhere you use pointers you should check they’re not null before using them. I usually do that by adding an IsValid()-style helper to the class and calling it where needed. For example:

 bool UXXXXXXX::IsValid() const
{
    return Propulsion != nullptr && Accelerations != nullptr;
} 

There’s at least one place where a pointer is being dereferenced without a check - please review each function that uses these pointers and add the validation.

P.S. I hope you are working with JSBSim through C++ only? Not through blueprints.