Access violation exception about chakra-samples HOT 4 CLOSED

Thanks for sharing :). I work on the JSRT team at Microsoft. Do you think you can share a repro/dump with us so that my team could take a closer look? If you don't want to share it publicly here, feel free to reach me at [email protected].

Limin [MSFT]

from chakra-samples.

Issue resolved offline.

from chakra-samples.

Could you please brief on how the issue got resolved. We are facing a similar issue. There is access violation exception/ engine execution exception whenever there is a call on UI thread and succeding calls on the JS thread results in exception.

from chakra-samples.

Thanks for asking, and yes of course.

On a high level, most of the AV issues here come from that in the C# app, installed callbacks are not retained and got garbage collected before being invoked. For example, you create a function like this,

//JsNativeFunction callback
private static JavaScriptValue nativeFunction(JavaScriptValue callee, bool isConstructCall, JavaScriptValue[] arguments, ushort argumentCount, IntPtr callbackData) 
{
    //do something here
}

...

JsCreateFunction(nativeFunction, callbackData, func);

The nativeFunction can be garbage collected. So instead you want to hold on to the delegate like in our sample and write,

//JsNativeFunction callback
private static JavaScriptValue nativeFunction(JavaScriptValue callee, bool isConstructCall, JavaScriptValue[] arguments, ushort argumentCount, IntPtr callbackData) 
{
    //do something here
}

private static readonly JavaScriptNativeFunction nativeFunctionDelegate = nativeFunction;

...

JsCreateFunction(nativeFunctionDelegate , callbackData, func);

Another trick is that you want to call JsAddRef on JavaScript objects that are not going to be stored somewhere on the stack; otherwise you may hit AV as well.

Given this appears to be a common problem, we will look into improving our documentation.

Thanks,
Limin Zhu
Chakra, Microsoft

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