From: Bill Kelly <billk@...>
Date: 2003-06-19T22:17:41+09:00
Subject: Re: TCP/IP protocol and Net::HTTP

Hi,

From: "Nigel Gilbert" <n.gilbert@soc.surrey.ac.uk>
> I am beginning to wonder if this problem arises from the MacOS X  
> implementation of ruby.
[...]
> On the other hand, I get the timeout error on MacOS X both at home  
> (with a cable modem connection) and at my university (with a direct  
> connection to the internet).

Hi, I get the same timeout on OS X (over a DSL business line)
with: ruby 1.6.7 (2002-03-01) [powerpc-darwin6.3]

I ran a tcpdump when executing the
Net::HTTP.get_print 'ad.doubleclick.net', '/'
line and was surprised to see NO tcp packets transmitted to
ad.doubleclick.net at any time.

I ran a ktrace - but it's my first time using it and I'm not
sure how to interpret what I'm seeing.. :)  Why is the SIGALRM
happening before the socket calls?  The call listed as taking
all the time is the "51.224883 CALL  socket(0x2,0x1,0x6)"...

 23026 ruby     0.001869 PSIG  SIGVTALRM caught handler=0x1a0334 mask=0x0 code=0x0
 23026 ruby     0.000121 CALL  sigreturn(0xbffcc660)
 23026 ruby     0.000047 RET   sigreturn JUSTRETURN
 23026 ruby     0.003751 CALL  gettimeofday(0xbffbc350,0)
 23026 ruby     0.000130 RET   gettimeofday 1056027683/0x3ef1b423
 23026 ruby     0.000040 CALL  gettimeofday(0xbffbc2b0,0)
 23026 ruby     0.000030 RET   gettimeofday 1056027683/0x3ef1b423
 23026 ruby     0.000032 CALL  gettimeofday(0xbffbbfe0,0)
 23026 ruby     0.000030 RET   gettimeofday 1056027683/0x3ef1b423
 23026 ruby     0.000029 CALL  select(0,0xbffbc050,0xbffbc0d0,0xbffbc150,0xbffbc1d0)
 23026 ruby     0.000036 RET   select 0
 23026 ruby     51.224883 CALL  socket(0x2,0x1,0x6)
 23026 ruby     0.000232 RET   socket 7
 23026 ruby     0.000042 CALL  fcntl(0x7,0x3,0)
 23026 ruby     0.000031 RET   fcntl 2
 23026 ruby     0.000071 CALL  fcntl(0x7,0x4,0x6)
 23026 ruby     0.000044 RET   fcntl 0
 23026 ruby     0.000030 CALL  connect(0x7,0x47eba0,0x10)
 23026 ruby     0.000120 RET   connect -1 errno 36 Operation now in progress
 23026 ruby     0.000056 CALL  gettimeofday(0xbffbe760,0)
 23026 ruby     0.000033 RET   gettimeofday 1056027734/0x3ef1b456
 23026 ruby     0.000029 CALL  select(0x9,0xbffbe7d0,0xbffbe850,0xbffbe8d0,0xbffbe950)
 23026 ruby     0.000038 RET   select 0
 23026 ruby     0.000974 CALL  gettimeofday(0xbffbc350,0)
 23026 ruby     0.000223 RET   gettimeofday 1056027734/0x3ef1b456
 23026 ruby     0.001292 CALL  sigprocmask(0x3,0x2178a4,0)
 23026 ruby     0.000132 RET   sigprocmask 0
 23026 ruby     0.001001 CALL  sigprocmask(0x3,0x2178a4,0)
 23026 ruby     0.000097 RET   sigprocmask 0
 23026 ruby     0.000107 CALL  write(0x1,0x342000,0xc)
 23026 ruby     0.000081 GIO   fd 1 wrote 12 bytes
       "TimeoutError"

...anyway... On a lark I became curious about DNS lookup time
and tried from the shell:

$ host ad.doubleclick.net

...and it took an awful long time to come back under OS X.

So from ruby I tried the literal IP addr for ad.doubleclick.net:

irb(main):007:0> Net::HTTP.get_print '216.73.86.70', '/'
<html>
<body bgcolor=#ffffff>
<b>This is a DoubleClick advertising server.</b>
<p><center>
<a href="http://www.doubleclick.net">
Click here for the DoubleClick home page.</a>
<p>
<a href="http://www.doubleclick.net/company_info/about_doubleclick/privacy/">
Click here for privacy information.</a>
</body>
</html>
nil

The above is under OS X...

So it *seems* maybe some DNS related thing under OS X and not 
Ruby specifically..... (?)



Hope this helps,

Bill