From: alexandre@...
Date: 2014-07-15T01:24:49+00:00
Subject: [ruby-core:63718] [ruby-trunk - Bug #10009] IO operation is 10x slower in multi-thread environment

Issue #10009 has been updated by Alexandre Riveira.


Hi Eric !

Eric Wong wrote:
> Good to know it works for you.  Keep in mind TIME_QUANTUM_USEC=1000 is


What problems do I have?

>  
>  Can you try 20-50ms?

In the application do a stress test where 5 threads overload.

I tested 50 and the latency is over the next 15 seconds.
I tested the latency is 20 and next 10 seconds.
I tested the latency is 10 and next 4 or 5 seconds.

The magic number is TIME_QUANTUM_USEC=1000. There is no latency in this case


Follow microbenckmars teste_thread_schedule_2 with postgres

TIME_QUANTUM_USEC (1000)
first 22882400
second 2654 <===
third 22642172
in 21.08 seconds

2654 / 21.08 is 125 connections for database per second


TIME_QUANTUM_USEC (20 * 1000)
first 33003617
second 258 <== 
third 33851933
in 23.07 seconds
258 / 23.07 is 11 connections for database per second. I think this small amount of connections per second but accept comments.


TIME_QUANTUM_USEC (50 * 1000)
first 42811975
second 116
third 42005480
in 25.12 seconds

116 / 25.12 is 5 connections for database per second.



----------------------------------------
Bug #10009: IO operation is 10x slower in multi-thread environment
https://bugs.ruby-lang.org/issues/10009#change-47765

* Author: Alexandre Riveira
* Status: Open
* Priority: Urgent
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.1 x ruby 1.9.2 with taskset
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
I created this issue #9832 but not have io operation.
In the script attached I simulate IO operation in multi-thread environment.
For ruby 1.9.2 apply `taskset -c -p 2 #{Process.pid}` for regulates threads behavior.
The second Thread is a io operation

My results:

1) ruby 2.1.2
first 43500194
second 95
third 42184385

2) ruby-2.0.0-p451
first 38418401
second 95
third 37444470

3) 1.9.3-p545
first 121260313
second 50
third 44275164

4) 1.9.2-p320
first 31189901
second 897 <============
third 31190598

Regards


Alexandre Riveira


---Files--------------------------------
teste_thread_schedule_2.rb (1.05 KB)
teste_thread_schedule.py (953 Bytes)
teste_thread_schedule.rb (955 Bytes)
test_thread_sched_pipe.rb (1.01 KB)


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