Bug #16658: `method__cache__clear` DTrace hook was dropped without replacement

• Status: Open
• Priority: Normal
• Assignee: ko1 (Koichi Sasada)
• Target version: -
• ruby -v: ruby 2.8.0dev (2020-02-26 master 83705c42ce) [x86_64-linux]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN

[vo.x (Vit Ondruch)]

The PR #2888 1 dropped DTrace method__cache__clear hook without replacement. Was this intentional? If yes, then the probes.d 3 should be updated appropriately. If this was not intentional, the hook should be reintroduced.

[vo.x (Vit Ondruch)]

• Related to Feature #16614: New method cache mechanism for Guild added

[vo.x (Vit Ondruch)]

• Assignee set to ko1 (Koichi Sasada)

@Koichi could you please take a look, since your commit removed the hook. Thx

[ko1 (Koichi Sasada)]

Sorry. what method__cache__clear did?
When this hook was invoked?

[vo.x (Vit Ondruch)]

ko1 (Koichi Sasada) wrote in #note-3:

Sorry. what method__cache__clear did?

I don't really know. tenderlovemaking (Aaron Patterson) is the author AFAIK. But this is the comment from probes.d:

     ruby:::method-cache-clear(class, filename, lineno);
     This probe is fired when the method cache is cleared.
     * `class` the name of the class or "global" (a string)
     * `filename` the file name where the cache is _being cleared_ (a string)
     * `lineno` the line number where the cache is _being cleared_ (an int)

When this hook was invoked?

https://github.com/ruby/ruby/pull/2888/files#diff-6cea7716df08f2b7fdc5fb30c7963884L98

[vo.x (Vit Ondruch)]

When this hook was invoked?

https://github.com/ruby/ruby/pull/2888/files#diff-6cea7716df08f2b7fdc5fb30c7963884L98

Hm, this does not appear to really work, since the vm_method.c is collapsed. Anyway, this used to be the invocation place:

https://github.com/ruby/ruby/blob/f2286925f08406bc857f7b03ad6779a5d61443ae/vm_method.c#L98

[ko1 (Koichi Sasada)]

Thanks, I think there is no chance to invoke this hook on current master.

[vo.x (Vit Ondruch)]

ko1 (Koichi Sasada) wrote in #note-6:

Thanks, I think there is no chance to invoke this hook on current master.

Could you please adjust the probes.d then? Thx.