Issue #21042 has been updated by byroot (Jean Boussier).
It should be similar to GC.stat. Maybe it should be accessible from other threads?
What about something like `GC.thread_stats(thread) # => {}`. This way it's understood that like `GC.stat`, the actual statistic are implementation dependent and can be there or not. Now of course if it is decided that it isn't per thread but per fiber, it would need another name.
However I'm afraid that people want to introduce many measurements per threads, or per fibers, and it can be overhead (speed and memory).
Indeed, if you wanted it on all 3 levels (Ractor/Thread/Fiber) this means 6 extra additions on every object allocation, might actually be significant in such an hot path. Yet another option could be to have a way to turn this off? Supposedly with branch prediction, checking a boolean first should be very little overhead. ---------------------------------------- Feature #21042: Add and expose Thread#memory_allocations memory allocation counters https://bugs.ruby-lang.org/issues/21042#change-112325 * Author: stanhu (Stan Hu) * Status: Open * Assignee: ioquatix (Samuel Williams) ---------------------------------------- For the last 5 years, we've been patching our Ruby interpreter with https://github.com/ruby/ruby/pull/3978 in order to track memory allocations over time. This has been running in production at GitLab for a long time. I'd like to request approval for this patch to land upstream since we're getting tired of maintaining this patch, and this data seems like it would be generally useful. If this can be done via a C extension, let me know, and I can look at that. Copying from that pull request: ### Design This is designed to measure a memory allocations in a multi-threaded environments (concurrent requests processing) with an accurate information about allocated memory within a given execution context. The idea here is to provide as cheap as possible counter without an overhead of calling callbacks, and provide this information on a per-thread basis. ### Implementation This adds `Thread.current.memory_allocations`, which provides information about: * total_allocated_objects * total_malloc_bytes * total_mallocs This is based on a expectation, that allocation for a given thread always happens with a `rb_current_thread()` properly indicating a thread performing allocation. This measures total number of allocations as counters. Now, since the removal of objects is async and happening at random moment, the same cannot be said for deallocations, thus only allocations are tracked. -- https://bugs.ruby-lang.org/