[ruby-core:112584] [Ruby master Feature#19465] [PATCH] reuse open(2) from rb_file_load_ok on POSIX-like system

Issue #19465 has been reported by normalperson (Eric Wong).

----------------------------------------
Feature #19465: [PATCH] reuse open(2) from rb_file_load_ok on POSIX-like system
https://bugs.ruby-lang.org/issues/19465

* Author: normalperson (Eric Wong)
* Status: Open
* Priority: Normal
----------------------------------------
```
When loading Ruby source files, we can save the result of
successful opens as open(2)/openat(2) are a fairly expensive
syscalls.  This also avoids a time-of-check-to-time-of-use
(TOCTTOU) problem.

This reduces open(2) syscalls during `require'; but should be
most apparent when users have a small $LOAD_PATH.  Users with
large $LOAD_PATH will benefit less since there'll be more
open(2) failures due to ENOENT.

With `strace -c -e openat ruby -e exit' under Linux, this
results in a ~14% reduction of openat(2) syscalls
(glibc uses openat(2) to implement open(2)).

 % time     seconds  usecs/call     calls    errors syscall
 ------ ----------- ----------- --------- --------- ----------------
   0.00    0.000000           0       296       110 openat
   0.00    0.000000           0       254       110 openat

Additionally, the introduction of `struct ruby_file_load_state'
may make future optimizations more apparent.

This change cannot benefit binary (.so) loading since the
dlopen(3) API requires a filename and I'm not aware of an
alternative that takes a pre-existing FD.  In typical
situations, Ruby source files outnumber the mount of .so
files.


I've only tested this lightly on small apps since I don't have
large codebases to test on.  However, I think organizing various
on-stack variables into `struct ruby_file_load_state' can be
beneficial if we end up using io-uring on Linux.
```


---Files--------------------------------
0001-reuse-open-2-from-rb_file_load_ok-on-POSIX-like-syst.patch (15.2 KB)


-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- [e-mail]
 To unsubscribe send an email to [e-mail]
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/