"loop do IO.select([io], nil, nil)" eats 95% of CPU, any other way?

[Iñaki Baz Castillo]

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Y0BhbGlheC5uZXQ+Cg==

 

[Robert Klemme]

Hi, which is the most efficient way of receiving and processing data
from a network socket?

I use GServer in this common way:

--------------
class MyServer < GServer
def serve(io)
loop do
if IO.select([io], nil, nil)
....
--------------

A "top" says to me that Ruby is eating more than 90% of CPU and there
is no connections yet...
Any other suggestion?

Really thanks a lot.

Why don't you simply use blocking IO?

robert

 

[James Tucker]

As a little side comment... You can _always_ take a program written
around a select & state machine and make it multi-threaded doing
blocking I/O or conversely refactor a multi-threaded app into a select
based state machine.

Assuming of course that a block in one thread won't block all other
threads.

 

[Iñaki Baz Castillo]

El Mi=C3=A9rcoles, 26 de Marzo de 2008, John Carter escribi=C3=B3:

Hmm.From the "man select" page...

timeout is an upper bound on the amount of time elapsed before
select() returns. It may be zero, causing select() to return
immediately. (This is useful for polling.) If timeout is NULL
(no timeout), select() can block indefinitely.

My guess is you have one too few nil's in there and the default timeout is
0 not nil.

Yes, true, with "strace" I see:

=2E..
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
select(4, [3], [], [], {0, 0}) =3D 0 (Timeout) <---
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
sigprocmask(SIG_BLOCK, NULL, []) =3D 0
=2E..


but I've tryed with all the values in the 4=C2=BA parameter of "IO.select":
IO.select([io], nil, nil, 0)
IO.select([io], nil, nil, nil)
IO.select([io], nil, nil, X)

and nothing changes, in all cases I see the same with "strace". =C2=BF?=C2=
=BF

to discover why linux is such a great place to develop on.... you can
_always_ find out what is really going on with any program.

Sure I use Linux... what else? XD

As a little side comment... You can _always_ take a program written
around a select & state machine and make it multi-threaded doing
blocking I/O or conversely refactor a multi-threaded app into a select
based state machine.

Of course I need to read a lot about IO methods


Thanks a lot.


=2D-=20
I=C3=B1aki Baz Castillo

 

[Iñaki Baz Castillo]

El Jueves, 27 de Marzo de 2008, John Carter escribi=C3=B3:

My guess is if you include the read statements you get something like
this... read(3, "", 1000) =3D 0
Which means (according to "man 2 read")

Which lib package must I install to get these man pages? I don't find them =
in=20
a Debian with default installation.

=3D=3Dtest.rb=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
loop do
begin
open( "foofi") do |f|
loop do
p select([f],nil,nil,500000)
p f.sysread(1000)
end
end
rescue EOFError =3D> details
p details
end
end
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Works as expected...

But...

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
open( "foofi") do |f|
loop do
p select([f],nil,nil,500000)
p f.sysread(1000)
end
end
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

Bombs out with EOFError

but curiously
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
open( "foofi") do |f|
loop do
p select([f],nil,nil,500000)
p f.read(1000)
end
end
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Exhibits exactly the behaviour you describe.

So it all behaves according to plan... just not your plan... )

Thanks a lot for so great information, it's really a good explanation.=20
Tomorrow I'll review all of it.


Thanks a lot for all and best regards.

=2D-=20
I=C3=B1aki Baz Castillo

 

[Marcelo]

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