RFR: 8317562: [JFR] Compilation queue statistics

[Vladimir Kozlov]

On Tue, 17 Oct 2023 00:35:54 GMT, Mat Carter <macarte at openjdk.org> wrote:

> Adding a new periodic jfr event to monitor and output statistics for the compiler queues.  You will see one event per compiler queue (c1 and c2)
> 
> Passes tier1 on linux (x86) and mac (aarch64)

Would be interesting to test it with Graal which use `c2_compile_queue` (Graal JIT replaces C2).

src/hotspot/share/compiler/compileBroker.cpp line 530:

> 528:   return _c2_compile_queue;
> 529: }
> 530: 

Note, `*_compiler_queue` could be `nullptr` if VM is build without C2 or C1 or when run with `-XX:-TieredCompilation` (only C2 is used) or with `-XX:TierdStopAtLevel={1,2,3}` (only C1 is used).

Make sure you check it in JFR event.

src/hotspot/share/compiler/compileBroker.hpp line 123:

> 121:   int         get_peak_size()     const          { return _peak_size; }
> 122:   int         get_total_added()   const          { return _total_added; }
> 123:   int         get_total_removed() const          { return _total_removed; }

Fields are `uint` type. These accessors should also return `uint`.

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PR Review: https://git.openjdk.org/jdk/pull/16211#pullrequestreview-1685714293
PR Review Comment: https://git.openjdk.org/jdk/pull/16211#discussion_r1364277126
PR Review Comment: https://git.openjdk.org/jdk/pull/16211#discussion_r1364268812