I also want to know how many of my request was failed because the server was unavailable (timed out).
About the timeout problems in LWP (perhaps a little off-topic?)
With unreachable hosts, LWP timeouts dont work (ex DNS problem).
Here is all relevant information I could gather, as I encounter that problem too (a single LWP request took several minutes, even when setting a 10 seconds timeout). See references and excerpts below.
To summarize, here are the underlying problems, as I understand them
1. &alarm() and signal handling dont work (well?) on win32 2. IO::Socket Linux Bug -- used &alarm(): upgrade to IO >= 1.20 3. LWP timeout start after making tcp connection (after DNS timeouts)
Excerpts --------
From [0]
$ua->timeout
$ua->timeout( $secs )
Get/set the timeout value in seconds.
The default timeout() value is 180 seconds, i.e. 3 minutes. The requests is aborted if no activity on the connection
to the server is observed for "timeout" seconds.
This means that the time it takes for the complete
transaction and the request() method to actually return
might be longer.From [1]
"This is a known bug in IO::Socket on Linux. If you upgrade your IO-modules things should get better. IO-1.20 or better does not use alarm to try to timeout connect(2)."
From [2]
"LWP relies on IO::Socket to do the connect timeout. Once it is connected it will do its own timeout before each read/write."
From [3]
"It's an issue with DNS timeout in IO::Socket::INET, apparently."
From [4]
"The timeout may seem to NOT work, if the host you're trying to connect is unreachable"
From [5]
"...if the host is unreachable, the timeout doesn't seems to work...
Or maybe the time out is only used once the TCP connections is done..."
"Under the covers, LWP uses SIGALRM (in IO::Socket) for timeouts. Unfortunately, signals aren't supported on Win32."
From [6]
alarm SECONDS
alarm Not implemented. (Win32)From [7]:
"Signal handling may not behave as on Unix platforms (where it doesn't exactly "behave", either :). For instance, calling "die()" or "exit()" from signal handlers will cause an exception, since most implementations of "signal()" on Win32 are severely crippled. Thus, signals may work only for simple things like setting a flag variable in the handler. Using signals under this port should currently be considered unsupported."
References ----------
[0] LWP manual page LWP::UserAgent(3pm)
[1] Re: LWP::UserAgent timeout / 29 Nov 1999 http://www.nntp.perl.org/group/perl.libwww/222
[2] Re: LWP and timeouts / 15 Oct 2003 http://www.nntp.perl.org/group/perl.libwww/5136
[3] Re: LWP and timeouts / 21 Oct 2003 http://www.nntp.perl.org/group/perl.libwww/5176
[4] LWP timeout / Apr 02, 2001 http://www.perlmonks.org/index.pl?node_id=68995
[5] LWP - timeout / Jan 26, 2001 http://www.perlmonks.org/index.pl?node_id=54528
[6] Perl 5.6.1 manual (5.8.4 is different about &alarm) perlport (1)
[7] Perl 5.6.1 manual (5.8.4 is same about signals) perlwin32(1)
