From: "Christoffer Lernö" <lerno@...>
Date: 2007-10-14T16:13:43+09:00
Subject: Re: write_nonblock is blocking?

On 14 Oct 2007, at 01:23, Eric Hodel wrote:

> On Oct 13, 2007, at 14:55 , Christoffer Lernö wrote:
>> Anyone know what's up with TCPSocket#write_noblock actually  
>> blocking when sending a packet that exceeds the buffer size of the  
>> socket in 1.8.6 on Mac.
>>
>> The behaviour seems slightly counter-productive.
>
> How long does it block?  I see ruby occasionally being delayed 10ms  
> when using write_nonblock, but not repeatably for the same packet  
> sizes.  Probably my benchmark script is wrong.
>
> Could you supply a benchmark script that illustrates your problem?
>
> #write_nonblock first does rb_io_check_closed() which might call  
> down to fseek(3) then write(2) before calling rb_io_set_nonblock 
> ().  I'm not even close to being a sockets expert though, I just  
> read the man pages.

Thanks. Know it "should work" made me try to analyze the situation.  
Here is an example code:

require 'socket'
a = TCPServer.new(5000)
socket = TCPSocket.new("localhost", 5000)

# Using a.accept will give a socket that does not exhibit problems,
# Only TCPServer#accept_nonblock seems to create this
# odd situation.

other = a.accept_nonblock
puts "Start Write"

# Lower values, say "X" * 2000, writes all in one sweep and does
# not cause it block

other.write_nonblock("X" * 300000)
puts "End Write"



It looks like write_nonblock together with accept_nonblock causes  
some issues.
Now I could be using these wrong as both are new (in 1.8.6?)


/Christoffer