RFR: 8264990: WebEngine crashes with segfault when not loaded through system classloader [v2]

[Matthias Bläsing]

On Mon, 12 Apr 2021 07:50:39 GMT, Johan Vos <jvos at openjdk.org> wrote:

> I understand the crash would be at a different point, but it would still be a crash, I think? That is, if the method handlers are correctly registered via the OnLoad function, and later a new native thread tries to access a function that is not yet attached, that will still crash, I believe. (at least, the GetEnv will return NULL and that result is used later).
> So while the 2 issues are not related, I think there are really 2 issues.

The question is: Is there a second issue? If all threads used in webkit are attached to the VM, any thread can directly fetch an `JNIEnv` instance from the `vm` interface and invoke methods. In this case the thread is correctly attached.

The problem here is/was, that the code path is not regularly exercised. My feeling is, that it is common, that the JavaFX modules are loaeded from the module path and loading JavaFX from a module layer / classpath (yes I know that this is not supported) is mostly untested.

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PR: https://git.openjdk.java.net/jfx/pull/458