RFR: 8371131: Cleanup Thread parameter in CollectedHeap TLAB methods

[Joel Sikström]

On Mon, 3 Nov 2025 09:49:02 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

> Hello,
> 
> The last usage of the the Thread parameter that is passed to `CollectedHeap::{tlab_capacity, tlab_used, unsafe_max_tlab_alloc}` was removed in [JDK-8370345](https://bugs.openjdk.org/browse/JDK-8370345). Following this we should remove the Thread parameter completely from CollectedHeap and all GCs that derive from it.
> 
> Testing:
> * Running through tier1-2

src/hotspot/share/gc/shared/threadLocalAllocBuffer.inline.hpp line 57:

> 55:   // Compute the size for the new TLAB.
> 56:   // The "last" tlab may be smaller to reduce fragmentation.
> 57:   // unsafe_max_tlab_alloc is just a hint.

I suggest we remove this comment as it is misleading since not all GCs take the `available_size` calculated here as a hint, but an unconditional size.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28107#discussion_r2485894298