Add -Xverify:none to docs for OpenJ9
#50
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@mandragorn is this specific to the Eclipse J9 virtual machine? The Jenkins platform SIG stopped efforts to support Eclipse J9 in 2021 because we did not have people with enough time to test it. If it is not specific to J9, are you still interested in this pull request and willing to resolve the conflicts? |
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Wow this is from a lifetime ago, I don't remember the details and I don't have whatever env I used to generate the issue (this was before I switched jobs). Based on the linked issue #37 and my comment there, it looks like I was testing this with the openjdk jvm, but I don't remember any details beyond that. I'm happy to rebase and push the update if you'd like me to. |
On newer versions of java bytecode is verified before it is run. Since this agent modifies core java bytecode it needs to bypass this verification. To turn the verification off pass -Xverify:none as an argument when running the agent. Fixed in unit tests and docs. Details: https://www.ibm.com/support/pages/ibm-java-linux-howto-resolving-javalangverifyerror-jvmvrfy012-stack-shape-inconsistent
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conflicts resolved. |
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-1 from me, I don't think we should be decreasing verification for HotSpot users (which this PR does by changing the recommendations for all JVMs in the documentation) in order to accommodate OpenJ9. If OpenJ9 requires a decrease in verification, I think that should be discussed in a separate section of the documentation.
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Docs updated. |
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Note that I think the bytecode generation that happens means that this doesn't work on any version of java beyond java 8 w/o If anyone has a way to test and confirm or deny those assumptions, let me know and I can update the docs as part of this commit. |
pom.xml
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| @@ -125,7 +125,7 @@ | |||
| <exclude>**/TransformerTest.java</exclude> | |||
| <exclude>**/AgentMainTest.java</exclude> | |||
| </excludes> | |||
| <argLine>-javaagent:"${project.build.directory}/file-leak-detector-${project.version}-jar-with-dependencies.jar"</argLine> | |||
| <argLine>-javaagent:"${project.build.directory}/file-leak-detector-${project.version}-jar-with-dependencies.jar" -Xverify:none</argLine> | |||
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This affects our test suite on HotSpot by decreasing verification. I think this PR should not affect HotSpot. The fact that this was working in our tests on HotSpot without -Xverify:none is evidence that this is only needed for OpenJ9.
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alright, sounds like this pr isn't needed. abandoning.
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The change to decrease verification on HotSpot in our test suite isn't needed (as far as I can tell) and isn't wanted (by me). The change to add additional documentation for OpenJ9 users seems valid to me though.
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I honestly don't remember a lot of details around this from 3 years ago. I think the issue I had was I couldn't run the tests locally because I had java9 setup, I had no idea it was a hotspot issue vs j9. I thought it was a java 8 vs java 9+ issue. I assume the test suite is running in something > java 8 at this point so my initial assumptions are wrong. I don't currently have the bandwidth to test this out in different jvms to see what works and what doesn't so I'm not sure how much value the documentation actually adds w/o those details. I guess I could make the docs more vague to cover it.
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We run the test suite with HotSpot (Eclipse Temurin) on Java 11 and 17. Yes, I think a general suggestion in the documentation for OpenJ9 users to run without verification should cover it.
basil
changed the title
-Xverify:none to docs for OpenJ9
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Thank you @basil for the feedback! |
This PR tries to address issue #37.
On newer versions of java bytecode is verified before it is run. Since
this agent modifies core java bytecode it needs to bypass this
verification. To turn the verification off pass -Xverify:none as an
argument when running the agent. Fixed in unit tests and docs.
Details: https://www.ibm.com/support/pages/ibm-java-linux-howto-resolving-javalangverifyerror-jvmvrfy012-stack-shape-inconsistent