Asp Forum - Threads: Different behavior under Linux and Windows

Armin Armbruster

7/8/2008 2:27:00 PM

Hi,

I've tried the sample code below on Ubuntu (7.04) as well as on a
Windows XP machine.
While under Linux I get the expected result, namely task 1 counting
away, under XP task 1 stalls until I enter something, then runs one loop
and stalls again.
I would have thought that the call to gets in task 2 only blocks task 2,
but not task 1.
Can anybody please explain this to me and more importantly show me a
solution on how to do this so it works under Windows as well?

Thanks in advance,
Armin

require 'thread'

t1 = Thread.new{
count = 0
loop{
count += 1
sleep 1
print "T1: #{count}\n"
}
}

t2 = Thread.new{
loop{
a = gets
print " T2: a = #{a}\n"
}
}

t1.join
t2.join
--
Posted via http://www.ruby-....

12 Answers

ara.t.howard

7/8/2008 2:47:00 PM

On Jul 8, 2008, at 8:26 AM, Armin Armbruster wrote:

> Can anybody please explain this to me and more importantly show me a
> solution on how to do this so it works under Windows as well?

it's well known - on windows *all* threads are blocked when the
process is blocked on IO.

a @ http://codeforp...
--
we can deny everything, except that we have the possibility of being
better. simply reflect on that.
h.h. the 14th dalai lama

Jochen Theodorou

7/8/2008 3:20:00 PM

ara.t.howard schrieb:
> On Jul 8, 2008, at 8:26 AM, Armin Armbruster wrote:
>
>> Can anybody please explain this to me and more importantly show me a
>> solution on how to do this so it works under Windows as well?
>
> it's well known - on windows *all* threads are blocked when the
> process is blocked on IO.

that sure is not because of windows itself... so is there a page
explaining why this is so?

bye Jochen

ara.t.howard

7/8/2008 3:27:00 PM

On Jul 8, 2008, at 9:16 AM, Jochen Theodorou wrote:

> that sure is not because of windows itself... so is there a page
> explaining why this is so?

http://groups.google.com/group/ruby-talk-google/search?group=ruby-talk-google&q=thread+block+windows&qt_g=Search+...

also, the pickaxe covers this in the 'threads and processes' chapter

a @ http://codeforp...
--
we can deny everything, except that we have the possibility of being
better. simply reflect on that.
h.h. the 14th dalai lama

Armin Armbruster

7/8/2008 5:59:00 PM

ara.t.howard wrote:
> On Jul 8, 2008, at 9:16 AM, Jochen Theodorou wrote:
>
>> that sure is not because of windows itself... so is there a page
>> explaining why this is so?
>
>
> http://groups.google.com/group/ruby-talk-google/search?group=ruby-talk-google&q=thread+block+windows&qt_g=Search+...
>
> also, the pickaxe covers this in the 'threads and processes' chapter
>
> a @ http://codeforp...

Thanks for your replies Ara.
I tried to find it in the pickaxe (second edition), Chapter 11, but I
couldn't find anything mentioned about this particular behavior under
Windows.
Also I tried to follow the discussion on google groups but didn't find a
solution described.

So now I'm stuck. Here's what I really want to do, maybe someone can
show me a solution to this?
I'd like to write a little terminal application.

1. Open a serial port
2. Create a sender task that waits for user input on stdin and sends the
data out the serial port.
3. Create a receiver task that waits for data coming from the serial
port and output it on the screen.

Any suggestions?

Thanks,
Armin
--
Posted via http://www.ruby-....

ara.t.howard

7/8/2008 6:17:00 PM

On Jul 8, 2008, at 11:59 AM, Armin Armbruster wrote:

> So now I'm stuck. Here's what I really want to do, maybe someone can
> show me a solution to this?
> I'd like to write a little terminal application.
>
> 1. Open a serial port
> 2. Create a sender task that waits for user input on stdin and sends
> the
> data out the serial port.
> 3. Create a receiver task that waits for data coming from the serial
> port and output it on the screen.
>
> Any suggestions?
>
> Thanks,
> Armin

seems like a class case of using select?

if select( [stdin, serial], nil, nil, 0.2 )
...

steve shreeve has had some luck using this paradigm:

require 'socket'

def socketpair
if RUBY_PLATFORM.include?("win32")
listen = TCPServer.new('127.0.0.1', 0)
client = TCPSocket.new('127.0.0.1', listen.addr[1])
server = listen.accept and listen.close
[client, server]
else
UNIXSocket.socketpair
end
end

c,s = socketpair

require 'win32/process'
info = Process.create(
'app_name' => 'cmd /c "type d:\four_megs.txt & pause"',
'startup_info' => {
'stdin' => c,
'stdout' => c,
}
)
c.close # needed?

to get nonblocking (in a thread) io on windows.

regards.

a @ http://codeforp...
--
we can deny everything, except that we have the possibility of being
better. simply reflect on that.
h.h. the 14th dalai lama

Armin Armbruster

7/8/2008 6:56:00 PM

ara.t.howard wrote:
> to get nonblocking (in a thread) io on windows.
>
>
>
> regards.
>
> a @ http://codeforp...

Thanks again Ara,

I'll give it a try.

Armin
--
Posted via http://www.ruby-....

Daniel Berger

7/8/2008 7:00:00 PM

On Jul 8, 8:46=A0am, "ara.t.howard" <ara.t.how...@gmail.com> wrote:
> On Jul 8, 2008, at 8:26 AM, Armin Armbruster wrote:
>
> > Can anybody please explain this to me and more importantly show me a
> > solution on how to do this so it works under Windows as well?
>
> it's well known - on windows *all* threads are blocked when the =A0
> process is blocked on IO.

It's actually a bug in MRI. JRuby does not exhibit that behavior, for
example. Park Heesob posted a patch a short while back that fixes it,
too. That patch has already been applied to Sapphire.

Regards,

Dan

Luis Lavena

7/9/2008 7:08:00 AM

On Jul 8, 5:19 pm, Jochen Theodorou <blackd...@uni.de> wrote:
> ara.t.howard schrieb:
>
> > On Jul 8, 2008, at 8:26 AM, Armin Armbruster wrote:
>
> >> Can anybody please explain this to me and more importantly show me a
> >> solution on how to do this so it works under Windows as well?
>
> > it's well known - on windows *all* threads are blocked when the
> > process is blocked on IO.
>
> that sure is not because of windows itself... so is there a page
> explaining why this is so?
>

No, is not a Windows problem but MRI Ruby Implementation Issue.

Ruby Threads are actually Green Threads (not real threads) so the
interpreter need to loop in them to be able to process them. When IO
is performed in the same thread (since 1.8 is single threaded) it
blocks and stop the green threads to be processed.

This is quite old actually, and been discussed several times here and
ruby-core (search for Io Thread and gets).

There was some changes introduced after p114 (1.8.6) but they needed
to be reverted because they introduced some issues on MinGW
compilation and Drb, which halt the tests (you can also look for that
in ruby-core)

At this time there is no solution for it, except to avoid that
scenario or jump to something like EventMachine to perform that task
(search for EventMachine Console in this forum).

HTH,
--
Luis Lavena

Luis Lavena

7/9/2008 10:07:00 PM

On Jul 8, 9:00 pm, Daniel Berger <djber...@gmail.com> wrote:
> On Jul 8, 8:46 am, "ara.t.howard" <ara.t.how...@gmail.com> wrote:
>
> > On Jul 8, 2008, at 8:26 AM, Armin Armbruster wrote:
>
> > > Can anybody please explain this to me and more importantly show me a
> > > solution on how to do this so it works under Windows as well?
>
> > it's well known - on windows *all* threads are blocked when the
> > process is blocked on IO.
>
> It's actually a bug in MRI. JRuby does not exhibit that behavior, for
> example. Park Heesob posted a patch a short while back that fixes it,
> too. That patch has already been applied to Sapphire.
>

Hey Dan, can you confirm if that patches make Drb tests stall or pass?
similar change introduced in 1.8 (but reverted due this) stall at
least for GCC.

Maybe we can give another shot at this and merge into 1.8 again.

Thank you,
--
Luis Lavena

Gordon Thiesfeld

7/10/2008 12:17:00 PM

On Wed, Jul 9, 2008 at 5:07 PM, Luis Lavena <luislavena@gmail.com> wrote:
>
> Hey Dan, can you confirm if that patches make Drb tests stall or pass?
> similar change introduced in 1.8 (but reverted due this) stall at
> least for GCC.
>
> Maybe we can give another shot at this and merge into 1.8 again.
>
> Thank you,
> --
> Luis Lavena
>
>

Also, a recently added spec in Rubyspec is hanging when using threads.
The code that hangs is in 1.8\library\socket\tcpsocket\shared\new.rb.
This is the failing example: http://pastie....

If you run:

>mspec 1.8/library/socket/tcpsocket

You should see it hang.

The offending code is run once for tcpsocket/new_spec.rb and once for
tcpsocket/open_spec.rb. If you run either file individually, no
problems. Do you think this is the same problem?

I've tested on these version:

ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32]
ruby 1.8.6 (2008-03-03 patchlevel 114) [i386-mingw32]
ruby 1.8.6 (2008-07-03 patchlevel 265) [i386-mingw32]

Thanks,

Gordon Thiesfeld

comp.lang.ruby

Threads: Different behavior under Linux and Windows

Armin Armbruster

ara.t.howard

Jochen Theodorou

ara.t.howard

Armin Armbruster

ara.t.howard

Armin Armbruster

Daniel Berger

Luis Lavena

Luis Lavena

Gordon Thiesfeld

x Login to ForumsZone