Integrated: 8300051: assert(JvmtiEnvBase::environments_might_exist()) failed: to enter event controller, JVM TI environments must exist

[Serguei Spitsyn]

On Thu, 20 Jul 2023 06:53:26 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

> This problem is encountered when a JVMTI agent is loaded into running VM. The JvmtiExport::get_jvmti_interface() is called from the agent's Agent_OnAttach entrypoint. To support virtual threads it enables JVMTI notifications from the VirtualThread class with a call to:
>   `JvmtiEnvBase::enable_virtual_threads_notify_jvmti()`.
> The problem is that there is no JVMTI environments at this point yet. This assert is hit when a virtual thread is created concurrently after the JVMTI notifications have been enabled but the requested JVMTI environment has not been created yet.
> The fix is to create a JVMTI env first and only then to enable the JVMTI notifications.
> 
> This issue is very hard to reproduce. I had to use some tricks with adding `os::naked_short_nanosleep()` and also by refactoring the test `VThreadTLSTest.java`. At least, I was able to verify this test does not fail with my fix anymore.
> 
> Testing:
>  - submitted hundreds of `VThreadTLSTest.java` mach5 runs on several platforms in the `fastdebug` mode
>  - in progress: mach5 tiers 1-6

This pull request has now been integrated.

Changeset: 783de32b
Author:    Serguei Spitsyn <sspitsyn at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/783de32b6af4383b5ba71b91c307a5dddd0dae13
Stats:     26 lines in 2 files changed: 14 ins; 12 del; 0 mod

8300051: assert(JvmtiEnvBase::environments_might_exist()) failed: to enter event controller, JVM TI environments must exist

Reviewed-by: dholmes, pchilanomate

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PR: https://git.openjdk.org/jdk/pull/14945