Feature #13951: [PATCH] File#rename releases GVL

• Status: Closed
• Assignee: -
• Target version: -

[normalperson (Eric Wong)]

rename(2) requires two pathname resolution operations which can
take considerable time on slow filesystems, release the GVL so
operations on other threads may proceed.

On fast, local filesystems, this change results in some slowdown
as shown by the new benchmark. I consider the performance trade
off acceptable as cases are avoided.

benchmark results:
minimum results in each 3 measurements.
Execution time (sec)
name    trunk   built
file_rename     2.648   2.804

Speedup ratio: compare with the result of `trunk' (greater is better)
name    built
file_rename     0.944

• file.c (no_gvl_rename): new function
  (rb_file_s_rename): release GVL for renames
• benchmark/bm_file_rename.rb: new benchmark

I will commit this next week as well as work on releasing GVL for
other operations where slow FS can have pathological slowdown
(unlink, link, symlink, readlink, readdir, mkdir, chmod, ...)

[normalperson (Eric Wong)]

[e-mail] wrote:

https://bugs.ruby-lang.org/issues/13951

Updated v2 with casts for 64-bit:

https://80x24.org/spew/[e-mail]/raw

(still using 32-bit for most dev work :x)

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)

normalperson (Eric Wong) wrote:

I consider the performance trade off acceptable as cases are avoided.

I agree that it would be small enough.

gcc for x86_64 warns:

file.c: In function 'no_gvl_rename':
file.c:2886:12: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
     return (void *)rename(ra->src, ra->dst);
            ^
file.c: In function 'rb_file_s_rename':
file.c:2914:9: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
     if ((int)rb_thread_call_without_gvl(no_gvl_rename, &ra,
         ^

• Status changed from Open to Closed

Applied in changeset trunk|r60091.

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NEWS: entries for GVL release in File and Dir

(more to come)

• NEWS: updates for [Bug #13941] and [Feature #13951]