RFR: 8349178: runtime/jni/atExit/TestAtExit.java should be supported on static JDK

[David Holmes]

On Tue, 4 Feb 2025 19:42:42 GMT, Jiangli Zhou <jiangli at openjdk.org> wrote:

>>> @jianglizhou I will be brutally honest and say that I do not like this at all. Does this mean all JNI using tests/applications have to becoded differently to be used with a static JDK? I find it somewhat ironic that to work with a static JDK we have to rewrite the test to perform a dynamic lookup!
>> 
>> A custom launcher will typically link to libjvm or use dlopen/dlym to get to JNI_CreateJavaVM. A static build isn't really suitable for custom launchers (or anything that embeds a VM).
>> 
>> So I think the changes to the test are okay if we really want to run this test with a static build. An alternative is to have the tests that use JNI_CreateJavaVM to not be selected. At some point I suspect we'll need to add a property to jtreg-ext/requires/VMProps.java for these builds anyway.
>
>> A static build isn't really suitable for custom launchers (or anything that embeds a VM).
> 
> Just want to provide some relevant data point. We build custom launcher and statically link with the libjvm (for hermetic case). If libjvm is statically linked with the launcher, then there's actually no need to change the direct calls to those JNI_ functions. The direct calls are not problematic on static build. 
> 
>> An alternative is to have the tests that use JNI_CreateJavaVM to not be selected. 
> 
> The alternative also sounds reasonable to me. We could skip running on static JDK if a test explicitly requires libjvm.so, libjava.so, etc at runtime, at least initially.
> 
>> At some point I suspect we'll need to add a property to jtreg-ext/requires/VMProps.java for these builds anyway.
> 
> That's a good point. We can add a `vm.static.jdk` to help test selection.

Thanks for clarifying @jianglizhou . Okay so the issue is only with the top-level invocation API functions:
 - JNI_GetDefaultJavaVMInitArgs
 - JNI_GetCreatedJavaVMs
 - JNI_CreateJavaVM
and as noted launchers have the choice of either linking with libjvm.so or else using dynamic lookup. The former doesn't work with a static JDK (can we link with libjvm.a?). So in the context of fixing a couple of tests this is okay.

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PR Comment: https://git.openjdk.org/jdk/pull/23431#issuecomment-2635480736