From: Christian Reiniger <creinig@...>
Date: 2004-11-24T05:21:24+09:00
Subject: Possible Bug: Running thread blocks access to /proc/loadavg

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=46ollowing code:

=2D---------
puts "Outside: " + File.read('/proc/loadavg')

t =3D Thread.new {
        sleep 3
}

puts "Outside 2: " + File.read('/proc/loadavg')
=2D----------

On my system, the "Outside 2:..." is never printed (ruby just hangs with=20
no CPU utilization). Just the existence of some spawned thread seems to=20
prevent access to /proc/loadavg.
Other files (e.g. /proc/cpuinfo) can be accessed just fine.
Putting the thing into the spawned thread generates the same behavior=20
(hang on the second File.read).
Using File.open with File::NONBLOCK instead of File.read does not change=20
anything.

chris@chrisbig > ruby --version
 ruby 1.8.2 (2004-11-06) [i686-linux]
chris@chrisbig > uname -a
 Linux chrisbig 2.6.9 #3 Tue Nov 23 21:28:15 CET 2004 i686 AMD Athlon(tm)=20
XP 2800+ AuthenticAMD GNU/Linux
chris@chrisbig > esearch -F -c dev-lang/ruby
 [ I] ruby (1.8.2_pre3):  An object-oriented scripting language

Same behavior with kernel 2.6.1-rc1.

On the following machine it works fine:

creinig@munin:~$ ruby --version
 ruby 1.8.2 (2004-11-03) [i386-linux]
creinig@munin:~$ uname -a
 Linux munin 2.4.27-1-386 #1 Fri Sep 3 06:24:46 UTC 2004 i686 GNU/Linux

A strace dump (from a run on the first machine) is available at=20
http://sunsite.dk/~creinig/tmp/loadavg-strace

Any idea?

=2D-=20
Christian Reiniger

Install once, run forever. Linux.

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