8353938: hotspot/jtreg/serviceability/dcmd/jvmti/LoadAgentDcmdTest.java fails on static JDK

[jianglizhou]

Please review this PR that changes LoadAgentDcmdTest.getLibInstrumentPath() to not locate libinstrument shared library if running on static JDK, instead just returns "libinstrument." directly. Both test case #1 and #2 in LoadAgentDcmdTest.run() run ok on static JDK with the change:

Commands:
Test case #1: JVMTI.agent_load libinstrument.so agent.jar
Test case #2: JVMTI.agent_load libinstrument.so "agent.jar=foo=bar"

Additional notes/considerations:

1. I notice JDKToolFinder.getJDKTool() is used by the test to find the jcmd tool. JDKToolFinder.getJDKTool() looks for the requested tool in both test.jdk and compile.jdk. When running the jtreg test on static JDK, it's able to locate the jcmd from compile.jdk even though the static JDK binary (test.jdk) does not provide the tool. For tools used by jtreg tests at runtime, how about change to always do that?

2. From https://docs.oracle.com/en/java/javase/21/docs/specs/man/jcmd.html:

JVMTI.agent_load [arguments]
Loads JVMTI native agent.
  Impact: Low
arguments:
  library path: Absolute path of the JVMTI agent to load. (STRING, no default value)
  agent option: (Optional) Option string to pass the agent. (STRING, no default value)

The command spec requires the absolute path of the JVMTI agent for the library path argument. On static JDK, if the agent library is built-in (statically linked), passing the shared library name works and allows the VM to find the built-in agent. There would be no need to specify the absolute path. Please see  https://bugs.openjdk.org/browse/JDK-8353938?focusedId=14767737&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14767737 for more details.

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Issue

• JDK-8353938: hotspot/jtreg/serviceability/dcmd/jvmti/LoadAgentDcmdTest.java fails on static JDK (Bug - P4)

Reviewers

• Alan Bateman (@AlanBateman - Reviewer)

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[openjdk]

@jianglizhou This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8353938: hotspot/jtreg/serviceability/dcmd/jvmti/LoadAgentDcmdTest.java fails on static JDK

Reviewed-by: alanb

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At the time when this comment was updated there had been 64 new commits pushed to the master branch:

• 5f2a604: 8353840: JNativeScan should not abort for missing classes
• 1f21da7: 8351462: Improve robustness of String concatenation
• 567c688: 8353597: Refactor handling VM options for AOT cache input and output
• ... and 61 more: https://git.openjdk.org/jdk/compare/5481021ee64fd457279ea7083be0f977c7ce3e3c...master

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[jianglizhou]

2. From https://docs.oracle.com/en/java/javase/21/docs/specs/man/jcmd.html:

JVMTI.agent_load [arguments]
Loads JVMTI native agent.
  Impact: Low
arguments:
  library path: Absolute path of the JVMTI agent to load. (STRING, no default value)
  agent option: (Optional) Option string to pass the agent. (STRING, no default value)

The command spec requires the absolute path of the JVMTI agent for the library path argument. On static JDK, if the agent library is built-in (statically linked), passing the shared library name works and allows the VM to find the built-in agent. There would be no need to specify the absolute path. Please see  https://bugs.openjdk.org/browse/JDK-8353938?focusedId=14767737&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14767737 for more details.

I discussed the JVMTI.agent_load issue on static support with @AlanBateman this morning as part of the hermetic Java meeting. @AlanBateman suggested considering adding an alternative diagnostic command or argument for the static (built-in) agent load support. We also discussed the use case of statically-linked dynamic (attached) native agents loaded by jcmd tool on static, and considerations for resolving (or clarifying) the JVMTI.agent_load static support at a later point when usage requirements were more clear. Outside the jtreg tests, I haven't run into any such usages yet.

Based on the discussion, I'll update this PR to skip the LoadAgentDcmdTest on static JDK for now.

I'll file a separate bug for the JVMTI.agent_load issue on static support so we can revisit that when things are more clear.

[jianglizhou]

I filed https://bugs.openjdk.org/browse/JDK-8354069.

[AlanBateman]

I assume you've bump the copyright header before integrating.

[jianglizhou]

I assume you've bump the copyright header before integrating.

Updated, thanks!

@AlanBateman Please help re-approve the PR.

[jianglizhou]

/integrate

[openjdk]

Going to push as commit faacbd9.
Since your change was applied there have been 65 commits pushed to the master branch:

• 6352ee1: 8349007: The jtreg test ResolvedMethodTableHash takes excessive time
• 5f2a604: 8353840: JNativeScan should not abort for missing classes
• 1f21da7: 8351462: Improve robustness of String concatenation
• ... and 62 more: https://git.openjdk.org/jdk/compare/5481021ee64fd457279ea7083be0f977c7ce3e3c...master

Your commit was automatically rebased without conflicts.

[openjdk]

@jianglizhou Pushed as commit faacbd9.

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