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List:       openjdk-serviceability-dev
Subject:    Re: RFR: 8287812: Cleanup JDWP agent GetEnv initialization [v2]
From:       Chris Plummer <cjplummer () openjdk ! org>
Date:       2022-12-14 19:38:07
Message-ID: KHVcHaqyWVPNL2-g0apO83GeljCr1DYP-ej5A-L2CVY=.e50b7732-8a55-44dd-962f-bbfe577f01a2 () github ! com
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On Fri, 9 Dec 2022 01:16:58 GMT, Chris Plummer <cjplummer@openjdk.org> wrote:

> > 3 things to cleanup in this area:
> > 
> > (1) The JDWP agent uses `JNI GetEnv(JVMTI_VERSION_1)` to get a JVMTI environment. \
> > If `GetEnv` fails the JDWP agent prints this: 
> > `ERROR: JDWP unable to access JVMTI Version 1 (0x30010000), is your J2SE a 1.5 or \
> > newer version? JNIEnv's GetEnv() returned -3` 
> > The text "is your J2SE a 1.5 or newer version?" dates from JDK 5 when JVMTI was \
> > introduced and doesn't make sense now. 
> > (2) `JVMTI_VERSION_1` suggests that the JDWP agent is looking for a JVMTI v1 \
> > environment when it really wants the latest. `GetEnv` should request \
> > `JVMTI_VERSION` so that it always requests the current version. 
> > (3) There is some outdated compatibility checking between runtime and compile \
> > time versions of JVMTI that date back to the 1.0, 1.1, and 1.2 era, and are no \
> > longer needed.
> 
> Chris Plummer has updated the pull request incrementally with one additional commit \
> since the last revision: 
> Get rid of some structs and statics that are no longer needed.

I'm going to stick with my change to use JVMTI_VERSION rather than JVMTI_VERSION_1. \
It seems that the agent really should be asking for the version it needs, not asking \
for a lesser version. Although the error message might not be as good if someone does \
placement of the debug agent into a different JDK build, no one should be doing this \
in the first place, and the resulting error message is still appropriate.

Thanks for the reviews Alan, Serguei, and Alex!

-------------

PR: https://git.openjdk.org/jdk/pull/11602


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