From: ruby-core--- via ruby-core <ruby-core@...>
Date: 2023-02-28T09:40:27+00:00
Subject: [ruby-core:112627] [Ruby master Feature#19465] [PATCH] reuse open(2) from rb_file_load_ok on POSIX-like system

Issue #19465 has been updated by hsbt (Hiroshi SHIBATA).


Copy Eric's message from [ruby-core:112626](https://ml.ruby-lang.org/mailman3/hyperkitty/list/ruby-core@ml.ruby-lang.org/message/GJTGY77GFCGBOAIFTSLEYYGO2ENSDR52/)

> 35136e1e9c232ad7a03407b992b2e86b6df43f63 is broken with `gcc-11 annocheck`.
>
> Its configuration is here:
> https://git.ruby-lang.org/ruby.git/tree/.github/workflows/compilers.yml#n82

      default_cc: 'gcc-11 -fcf-protection -Wa,--generate-missing-build-notes=yes'
      optflags: '-O2'
      LDFLAGS: '-Wl,-z,now'

OK, only gcc11-available system I have is a FreeBSD VM and I
couldn't reproduce it with those flags, (no podman/docker on
FreeBSD).

> 69 1)  An exception occurred during: Kernel#require_relative with a
> relative path (file extensions) does not load a C-extension file if a
> complex-extensioned .rb file is already loaded
> 70 /__w/ruby/ruby/src/spec/ruby/core/kernel/require_relative_spec.rb:197
> 71 Kernel#require_relative with a relative path (file extensions) does
> not load a C-extension file if a complex-extensioned .rb file is
> already loaded ERROR
> 72 LeakError: Leaked file descriptor: 8 :
> #<File:/__w/ruby/ruby/src/spec/ruby/fixtures/code/load_fixture.ext.rb>

I saw similar errors in development, but thought I fixed them all.
Where there other CI instances which failed or just the annocheck one?
I can't find failures for 35136e1e9 in http://ci.rvm.jp/failure_results

Is there a machine/VM I can ssh/mosh into which reproduces that issue?

Thanks.


----------------------------------------
Feature #19465: [PATCH] reuse open(2) from rb_file_load_ok on POSIX-like system
https://bugs.ruby-lang.org/issues/19465#change-102078

* Author: normalperson (Eric Wong)
* Status: Assigned
* Priority: Normal
* Assignee: normalperson (Eric Wong)
----------------------------------------
```
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)


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