[ruby-core:95272] [Ruby master Feature#16245] Add interfaces to count and measure size all IMEMO objects

Issue #16245 has been updated by methodmissing (Lourens Naud薊.


sam.saffron (Sam Saffron) wrote:
> Koichi introduced an experimental gem: https://github.com/ko1/iseq_collector
> 
> It allows:
> 
> ObjectSpace.each_iseq{|iseq| ...}
> ObjectSpace.count_iseq #=> Integer
> ObjectSpace.memsize_of_all_iseq (should not generate RubyVM::InstructionSequence wrappers for IMEMOs)
> 
> Since the wrapper object  RubyVM::InstructionSequence is lazily allocated, ObjectSpace.each_object does not find these IMEMOs unless they have been wrapped. This design is good and conserves memory. 
> 
> `count_iseq` and `memsize_of_all_iseq` are very powerful metrics most large Ruby deployments can use to automatically detect method leaks introduced via meta programming. These issues are invisible now short of walking a heap dump. 
> 
> Can we add the new interface into 2.7?

I worked on `imemo_memsize` some time ago to correctly reflect the type sizes in https://github.com/ruby/ruby/commit/90c4bd2d2bd10b19c2b09834396553742bc7e8a4 which makes heap dumps more accurate. I understand the API proposal, but also I believe the intention was for these objects to be internal and not necessarily to be exposed through API. However I do suspect for large Rails applications their combined footprint can add up, especially for the types that can allocate heap memory too:

* imemo_ment (method entries)
* imemo_iseq (as per your description above)
* imemo_env (bindings)
* imemo_tmpbuf (tried to support these on the transient heap but found them to be almost never used much in practice as it appears to be a fallback for `ALLOCA` under some circumstances.
* imemo_ast

I have not had any free time to investigate further, but I think this is an interesting storage class to explore further and I'd be interesting in helping, whichever way the proposal goes.

----------------------------------------
Feature #16245: Add interfaces to count and measure size all IMEMO objects
https://bugs.ruby-lang.org/issues/16245#change-81948

* Author: sam.saffron (Sam Saffron)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
Koichi introduced an experimental gem: https://github.com/ko1/iseq_collector

It allows:

ObjectSpace.each_iseq{|iseq| ...}
ObjectSpace.count_iseq #=> Integer
ObjectSpace.memsize_of_all_iseq (should not generate RubyVM::InstructionSequence wrappers for IMEMOs)

Since the wrapper object  RubyVM::InstructionSequence is lazily allocated, ObjectSpace.each_object does not find these IMEMOs unless they have been wrapped. This design is good and conserves memory. 

`count_iseq` and `memsize_of_all_iseq` are very powerful metrics most large Ruby deployments can use to automatically detect method leaks introduced via meta programming. These issues are invisible now short of walking a heap dump. 

Can we add the new interface into 2.7?



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