# \[Bug:1.9\] thread switch when heavy load

**URL:** <https://www.ruby-forum.com/t/bug-1-9-thread-switch-when-heavy-load/160938>\
**Category:** Development\
**Created:** [February 21, 2009, 4:26am UTC](https://www.ruby-forum.com/t/bug-1-9-thread-switch-when-heavy-load/160938 "2009-02-21T04:26:17Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Tanaka\_A](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/c67d28/32.png) [@Tanaka\_A](https://www.ruby-forum.com/u/Tanaka_A)\
**Post date:** [February 21, 2009, 4:26am UTC](https://www.ruby-forum.com/t/bug-1-9-thread-switch-when-heavy-load/160938/1 "2009-02-21T04:26:17Z")

</div>

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% cat /etc/debian\_version  
4.0  
% uname -a  
Linux nute 2.6.18-6-486 #1 Fri Dec 12 16:18:30 UTC 2008 i686 GNU/Linux  
% ruby -ve ’  
p $$  
r, w = IO.pipe  
Thread.new {  
begin  
t1 = Time.now  
loop {  
s = r.sysread(10)  
t2 = Time.now  
p [t2-t1, s]  
t1 = t2  
}  
ensure  
p $!  
end  
}  
loop { w.write “a”; sleep 1 }  
’  
ruby 1.9.2dev (2009-02-15 trunk 22328) [i686-linux]  
16259  
[1.5086e-05, “a”]  
[1.001370774, “a”]  
[1.004141531, “a”]  
[1.004539908, “a”]  
[1.003810203, “a”]  
[1.003755167, “a”]  
[1.004224783, “a”]  
[1.003889822, “a”]  
[1.004372847, “a”]  
[2.163765927, “a”]  
[15.54612696, “a”]  
[1.009049164, “a”]  
[1.002022536, “a”]  
…

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% strace -p 16259  
Process 16259 attached - interrupt to quit  
sched\_yield() = 0  
sched\_yield() = 0  
sched\_yield() = 0  
sched\_yield() = 0  
sched\_yield() = 0  
sched\_yield() = 0  
sched\_yield() = 0  
sched\_yield() = 0  
sched\_yield() = 0  
sched\_yield() = 0  
…

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