Re: Why is the CPAN shell not DWIMming?

jkeenan1 wrote:

Are the long delays I'm experiencing due to the fact that ftp.perl.org is the first place my shell looks? Or are the delays due to LWP::UserAgent and Net::FTP, which never seem to work?

The long delays are due to the failures of LWP::UserAgent and Net::FTP. CPAN will continue to try those approaches to retrieving the needed files from the mirror host until the lengthy failure timeouts are reached, then will (as reported) fall back to a less sophisticated means. The intelligence to "observe" the previous failures is not part of CPAN, and this is the most frequent valid complaint I hear from Perl users about that software. Note please the qualifiers: frequent and valid. There are numerous other complaints, some of which I regard as not valid (they seem based on what are to me, expectations of the software that are not part of the stated interface, goals or point of the system); and there are other less-frequently raised complaints that I regard as valid.

LWP::UserAgent has worked in CPAN for me on most machines I use, eventually, but sometimes I have had to reinstall newer releases of it or otherwise fiddle with something. As for the mirror host, that is the most common cause of failure in my experience, and deserves attention. I do not enjoy the exasperation of having a failure to connect to a configured host block my work, so I worked out some code (posted on my home node) that checks the list of configured hosts before trying to do anything else in CPAN's shell. It is not necessary to go through the entire (lengthy, tedious, error-prone, somewhat confusing for new users) CPAN configuration session that is invoked by doing in the CPAN shell " o conf init ", just to change the list of mirror hosts. Some newer CPAN users most likely would think that it is, so I mention it here.

Soren A / somian / perlspinr / Intrepid

Comment on Re: Why is the CPAN shell not DWIMming?

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Re^2: Why is the CPAN shell not DWIMming? by jkeenan1 (Deacon) on Jun 22, 2005 at 22:50 UTC
Intrepid wrote: The long delays are due to the failures of LWP::UserAgent and Net::FTP. CPAN will continue to try those approaches to retrieving the needed files from the mirror host until the lengthy failure timeouts are reached, then will (as reported) fall back to a less sophisticated means. Let me provide some more data that may provide experienced monks with a clue to the solution. Once I solved the permissions problem (see other posting), I tackled the question of the mirror I was using. I studied the documentation in CPAN.pm and learned that I could define preferences by making changes in $HOME/.cpan/CPAN/MyConfig.pm. I discovered that I had no such file, perhaps because I had never attempted to make configuration changes since installing 5.8.4. So I copied over /usr/local/lib/perl5/5.8.4/CPAN/Config.pm and, after some trial and error, added the following values: Read more... (372 Bytes) I'd used all three of these mirrors previously. I then decided to test this configuration by installing a module with relatively few prerequisites and no .XS: `brian d foy`'s Test::Data. To my chagrin, I experienced the same type of delays I'd experienced with ftp.perl.org. Read more... (2 kB) Only after failing with both LWP::UserAgent and Net::FTP on each of the three mirrors did CPAN.pm finally do the right thing: `Issuing "/usr/bin/ftp -n" Connected to shadow.cc.columbia.edu. 220- WELCOME to the FTP archives at mirror.cc.columbia.edu ...` [download] Read more... (960 Bytes) ... at which point the installation went like a bat outta hell. This is consistent with what Intrepid reported he has seen. The one new datum I'd like to add is this: I experience similarly long delays when using ftp on my iBook -- but I don't when using it on my Linux or Windows boxes. Suppose I'm ftp-ing to my own web space: `ftp> cd Storage 250 CWD command successful. ftp> ls 229 Entering Extended Passive Mode (\|\|\|57117\|) 500 Illegal EPRT command 200 PORT command successful` [download] I know from experience that at `ls` or `dir`, the service will hang and in all likelihood time out -- as it did just now as I was testing it. This was the outcome: `421 Service not available, remote server timed out. Connection closed` [download] It's the Extended Passive Mode I'm suspicious of. I don't get that on my other boxes; I get plain Passive Mode on those. I posted this problem on the ny.pm mailing list earlier this year, and Ben Holtzman turned me on to the program lftp written by a Russian hacker and available (I think) on Sourceforge. I have no problem using lftp (or, for that matter, the Mac ftp client Fetch) ... except when I have a script that uses Net::FTP. So I'm wondering if the problem is not with ftp.perl.org but with the version of ftp that comes with Mac OS X. But if that's the case, why did `/usr/bin/ftp -n` succeed where LWP::UserAgent and Net::FTP failed? It just gets more mysterious! jimk	[reply] [d/l] [select]

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Re^2: Why is the CPAN shell not DWIMming?
by jkeenan1 (Deacon) on Jun 22, 2005 at 22:50 UTC

The long delays are due to the failures of LWP::UserAgent and Net::FTP. CPAN will continue to try those approaches to retrieving the needed files from the mirror host until the lengthy failure timeouts are reached, then will (as reported) fall back to a less sophisticated means.

Let me provide some more data that may provide experienced monks with a clue to the solution.

Once I solved the permissions problem (see other posting), I tackled the question of the mirror I was using. I studied the documentation in CPAN.pm and learned that I could define preferences by making changes in $HOME/.cpan/CPAN/MyConfig.pm. I discovered that I had no such file, perhaps because I had never attempted to make configuration changes since installing 5.8.4. So I copied over /usr/local/lib/perl5/5.8.4/CPAN/Config.pm and, after some trial and error, added the following values:

Read more... (960 Bytes)

... at which point the installation went like a bat outta hell. This is consistent with what Intrepid reported he has seen.

The one new datum I'd like to add is this: I experience similarly long delays when using ftp on my iBook -- but I don't when using it on my Linux or Windows boxes. Suppose I'm ftp-ing to my own web space:

ftp> cd Storage
250 CWD command successful.
ftp> ls
229 Entering Extended Passive Mode (|||57117|)
500 Illegal EPRT command
200 PORT command successful
[download]

I know from experience that at ls or dir, the service will hang and in all likelihood time out -- as it did just now as I was testing it. This was the outcome:

421 Service not available, remote server timed out. Connection closed
[download]

It's the Extended Passive Mode I'm suspicious of. I don't get that on my other boxes; I get plain Passive Mode on those.

I posted this problem on the ny.pm mailing list earlier this year, and Ben Holtzman turned me on to the program lftp written by a Russian hacker and available (I think) on Sourceforge. I have no problem using lftp (or, for that matter, the Mac ftp client Fetch) ... except when I have a script that uses Net::FTP.

So I'm wondering if the problem is not with ftp.perl.org but with the version of ftp that comes with Mac OS X. But if that's the case, why did /usr/bin/ftp -n succeed where LWP::UserAgent and Net::FTP failed?

It just gets more mysterious!

jimk

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