RFR: 8324241: Always record evol_method deps to avoid excessive method flushing [v2]

[John R Rose]

On Mon, 22 Jan 2024 23:26:08 GMT, Evgeny Astigeevich <eastigeevich at openjdk.org> wrote:

>> Volker Simonis has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Guard the feature with a diagnostic option and update the comments in the code
>
> src/hotspot/share/runtime/globals.hpp line 2013:
> 
>> 2011:           "Profile exception handlers")                                     \
>> 2012:                                                                             \
>> 2013:   product(bool, AlwaysRecordEvolDependencies, true, DIAGNOSTIC,             \
> 
> As we record all dependencies not only evol_method ones, should we name it just: `AlwaysRecordDependencies`?

That’s not exactly right either.  `RecordAllDependencies` would be more like it.  Because:

  - We might record some dependencies that we know we need, and leave others out.
  - Or, we might record all dependencies, even ones we think we might not need.

(But we will need them all if somebody turns on JFR.)

I like this change.  Having a diagnostic switch means we can do a rough triage if something seems to go wrong with this change, down the road.

> src/hotspot/share/runtime/globals.hpp line 2014:
> 
>> 2012:                                                                             \
>> 2013:   product(bool, AlwaysRecordEvolDependencies, true, DIAGNOSTIC,             \
>> 2014:                 "Unconditionally record method dependencies on class "      \
> 
> "... record compiled method dependencies ..."?

(yes, “compiled methods” or even “nmethods”, or “methods in code cache”)

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PR Review Comment: https://git.openjdk.org/jdk/pull/17509#discussion_r1462556769
PR Review Comment: https://git.openjdk.org/jdk/pull/17509#discussion_r1462557389