RFR: 8365932: Implementation of JEP 516: Ahead-of-Time Object Caching with Any GC [v10]

[Erik Österlund]

On Tue, 28 Oct 2025 10:44:58 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> We have loads of JavaThreads that don't run Java code (e.g. service thread, compiler threads, string dedup thread, monitor deflation thread). The window of time in which it lacks a Thread object, is before we start executing Java byte codes at all. But like those other threads I mentioned, it does not have any business executing Java code, despite being a JavaThread. It is a JavaThread because I want it to have a TLAB so it can efficiently allocate objects in the heap.
>
> Sorry I should have said "run Java code and/or interact with oops" - though even that may be incomplete. Okay point taken though the others still get their Thread oop before they start. Having a new "JavaThread" running around before even the main thread is fully attached may surprise some code.

The main thread still attaches first. The main thread, like this new AOT thread, attaches before it has a thread oop. They both have their thread oops created inside of Threads::initialize_java_lang_classes after the Thread class has been initialized.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27732#discussion_r2470178073