<AWT Dev> RFR: 8170493: JNI exception pending in JavaComponentAccessibility.m:142

[Phil Race]

Sergey,

Any [additonial] comment on this ?

-phil.

On 01/26/2017 01:55 PM, Philip Race wrote:
> LIke I said in the bug report, if we get OOME here then we'll get more
> from the following calls and if we want to make this accessibility 
> code robust
> against this theoretical problem a massive destabilising re-write is 
> needed.
>
> How about this change instead
> --- 
> a/src/java.desktop/macosx/native/libawt_lwawt/awt/JavaComponentAccessibility.m
> +++ 
> b/src/java.desktop/macosx/native/libawt_lwawt/awt/JavaComponentAccessibility.m
> @@ -136,7 +136,7 @@
>          fJavaRole = [javaRole retain];
>
>          fAccessible = (*env)->NewWeakGlobalRef(env, accessible);
> -
> +        (*env)->ExceptionClear(env); // in case of OOME
>          jobject jcomponent = [(AWTView *)fView awtComponent:env];
>          fComponent = (*env)->NewWeakGlobalRef(env, jcomponent);
>          (*env)->DeleteLocalRef(env, jcomponent);
>
> -----
>
> ExceptionClear is harmless if there is no exception pending.
> And we will be "using jni correctly" in making the next call to 
> NewWeakGlobalRef
> .. .even if it fails.
>
> fAccessible is mostly guarded against use of NULL so it might even 
> make things better
> but definitely won't harm anything.
>
> If we ever see a real issue here that de-stabilising re-write will be 
> needed.
> But not in JDK 9.
>
> Its either make the mostly useless small change or "will not fix" but
> we are supposed to be fixing these JNI correctness bugs.
>
> -phil.
>
> On 1/16/17, 7:17 AM, Sergey Bylokhov wrote:
>> Hi, Phi.
>>> // these constants are duplicated in CAccessibility.java
>>> @@ -136,7 +137,7 @@
>>>          fJavaRole = [javaRole retain];
>>>
>> I am not sure but it seems strange that we will return the "self"(and 
>> will use it later), because it is not nil and was not properly 
>> initialized (for example fActionsLOCK field which is used for 
>> synchronization will be nil).