[ruby-core:101931] [Ruby master Bug#17497] Ractor performance issue
From:
ko1@...
Date:
2021-01-05 08:08:54 UTC
List:
ruby-core #101931
Issue #17497 has been updated by ko1 (Koichi Sasada).
master_ruby and ruby was same, so not needed.
with version information:
```
26_mini ruby 2.6.7p148 (2020-06-14 revision 67884) [x86_64-linux]
27_mini ruby 2.7.3p139 (2020-10-11 revision d1ba554551) [x86_64-linux]
miniruby ruby 3.1.0dev (2021-01-05T07:50:00Z master e91160f757) [x86_64-linux]
26_ruby ruby 2.6.7p148 (2020-06-14 revision 67884) [x86_64-linux]
27_ruby ruby 2.7.3p139 (2020-10-11 revision d1ba554551) [x86_64-linux]
ruby ruby 3.1.0dev (2021-01-05T07:50:00Z master e91160f757) [x86_64-linux]
method: task_range_inject
user system total real
serial/26_mini 0 0.000330 0.000000 1.334362 ( 1.334173)
serial/27_mini 0 0.000401 0.000000 1.111259 ( 1.111157)
serial/miniruby 0 0.000388 0.000000 1.803708 ( 1.803610)
serial/26_ruby 0 0.000283 0.000000 1.274182 ( 1.274051)
serial/27_ruby 0 0.000243 0.000000 1.102547 ( 1.102493)
serial/ruby 0 0.000340 0.000000 1.892771 ( 1.892611)
r_serial/26_mini N/A
r_serial/27_mini N/A
r_serial/miniruby 1 0.000271 0.000000 2.484844 ( 2.485867)
r_serial/26_ruby N/A
r_serial/27_ruby N/A
r_serial/ruby 1 0.000308 0.000000 2.736252 ( 2.737059)
r_parallel/26_mini N/A
r_parallel/27_mini N/A
r_parallel/miniruby 1 0.000232 0.000000 20.958254 ( 5.828039)
r_parallel/26_ruby N/A
r_parallel/27_ruby N/A
r_parallel/ruby 1 0.000396 0.000000 22.323984 ( 6.165640)
```
----------------------------------------
Bug #17497: Ractor performance issue
https://bugs.ruby-lang.org/issues/17497#change-89779
* Author: marcandre (Marc-Andre Lafortune)
* Status: Open
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
* ruby -v: ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-darwin18]
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
There's a strange performance issue with Ractor (at least on MacOS, didn't run on other OS).
I ran a benchmark doing 3 different types of work:
* "fib": method calls (naive fibonacci calculation)
* "cpu": `(0...1000).inject(:+)`
* "sleep": call `sleep`
I get the kind of results I was excepting for the `fib` and for sleeping, but the results for the "cpu" workload show a problem.
It is so slow that my pure Ruby backport (using Threads) is 65x faster on my Mac Pro (despite having 6 cores). Expected results would be 6x slower, so in that case Ractor is 400x slower than it should 仭
On my MacBook (2 cores) the results are not as bad, the `cpu` workload is 3x faster with my pure-Ruby backport (only) instead of ~2x slower, so the factor is 6x too slow.
```
$ gem install backports
Successfully installed backports-3.20.0
1 gem installed
$ ruby ractor_test.rb
<internal:ractor>:267: warning: Ractor is experimental, and the behavior may change in future versions of Ruby! Also there are many implementation issues.
fib: 110 ms | cpu: 22900 ms | sleep: 206 ms
$ B=t ruby ractor_test.rb
Using pure Ruby implementation
fib: 652 ms | cpu: 337 ms | sleep: 209 ms
```
Notice the `sleep` run takes similar time, which is good, and `fib` is ~6x faster on my 6-core CPU (and ~2x faster on my 2-core MacBook), again that's good as the pure ruby version uses Threads and thus runs with a single GVL.
The `cpu` version is the problem.
Script is here: https://gist.github.com/marcandre/bfed626e538a3d0fc7cad38dc026cf0e
--
https://bugs.ruby-lang.org/
Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>