RFR: 8317562: [JFR] Compilation queue statistics [v3]

[Mat Carter]

On Sun, 29 Oct 2023 20:19:21 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> Mat Carter has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Addressed review comments
>
> src/hotspot/share/jfr/metadata/metadata.xml line 853:
> 
>> 851:   <Event name="CompilerQueueUtilization" category="Java Virtual Machine, Compiler" label="Compiler Queue Utilization" period="everyChunk">
>> 852:     <Field type="CompilerType" name="compiler" label="Compiler" />
>> 853:     <Field type="long" contentType="hertz" name="ingress" label="Ingress" description="Number of added requests per second"/>
> 
> Could we use other terms then ingress and egress? Something that is more in general use,

Thought about enqueue/dequeue, but went with added/removed so its consistent with the other fields

> src/hotspot/share/jfr/metadata/metadata.xml line 861:
> 
>> 859:     <Field type="long" name="totalAdded" label="Total Added"/>
>> 860:     <Field type="long" name="totalRemoved" label="Total Removed"/>
>> 861:     <Field type="int" name="compilerThreadCount" label="Number of Compiler Threads for this queue"/>
> 
> The label should be short and use headline-style capitalization, how about "Compiler Thread Count"?
> https://docs.oracle.com/en/java/javase/21/docs/api/jdk.jfr/jdk/jfr/Label.html

Fixed, thank you for the reference

> src/hotspot/share/jfr/periodic/jfrCompilerQueueUtilization.cpp line 53:
> 
>> 51:     return 0;
>> 52:   }
>> 53:   return ((current - old) * NANOSECS_PER_SEC) / interval.nanoseconds();
> 
> Shouldn't it be ticks per second here?

This resolves to ticks per second; could replace with (current - old) / interval.seconds() but this introduces floats.  This was taken from NetworkUtilization, I assume they went this way to keep the math in integers

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PR Review Comment: https://git.openjdk.org/jdk/pull/16211#discussion_r1379036697
PR Review Comment: https://git.openjdk.org/jdk/pull/16211#discussion_r1379037454
PR Review Comment: https://git.openjdk.org/jdk/pull/16211#discussion_r1379039332