On Tue, 19 Mar 2024 17:46:31 GMT, Tobias Holenstein <tholenst...@openjdk.org> wrote:
>> I've asked this myself (after making the change). >> Being in `WXWrite` mode would be wrong if the thread would execute >> dynamically generated code. There's not too much happening outside the scope >> of the `ThreadInVMfromNative` instances. I see jni calls >> (`GetObjectArrayElement`, `ExceptionOccurred`) and a jvmti call >> (`RetransformClasses`) but these are safe because the callees enter the vm >> right away. We even avoid switching to `WXWrite` and back there. >> So I thought it would be ok to coarsen the WXMode switching. >> But maybe it's still better to avoid any risk especially since there's >> likely no performance effect. > > Or could the `ThreadInVMfromNative tvmfn(THREAD);` in > `check_exception_and_log` be move out to > `JfrJvmtiAgent::retransform_classes`? And then only use one > `ThreadInVMfromNative` in `JfrJvmtiAgent::retransform_classes` I think this would require hoisting the `ThreadInVMfromNative` out of the loop with the `check_exception_and_log` call but then the thread would be in `_thread_in_vm` when doing the `GetObjectArrayElement` jni call which would be wrong. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/18238#discussion_r1532121487
