Dear Maintainer,

I am a new user of haskell-platform. After I installed it, I simply run:
cabal update, it hangs, then I try to use --verbose=3 to see what happend:

$ cabal update --verbose=3
Downloading the latest package list from hackage.haskell.org
Sending:
GET /packages/archive/00-index.tar.gz HTTP/1.1
Host: hackage.haskell.org
User-Agent: cabal-install/1.16.0.2
Creating new connection to hackage.haskell.org
Received:
HTTP/1.1 301 Moved Permanently
Server: nginx/1.4.2
Date: Sun, 03 Nov 2013 11:28:43 GMT
Content-Type: text/plain; charset=UTF-8
Transfer-Encoding: chunked
Connection: keep-alive
Location: /packages/index.tar.gz
Content-Length: 0
301 - redirect
Redirecting to http://hackage.haskell.org/packages/index.tar.gz ...
Sending:
GET /packages/index.tar.gz HTTP/1.1
Host: hackage.haskell.org
User-Agent: cabal-install/1.16.0.2
Recovering connection to hackage.haskell.org

It hangs after the last output line of "Recovering connecton to hackage.haskell.org"
I don't know if it is related to cabal-install itself or something else. however I
did additional tests:

1) proxychains cabal update,

$ proxychains cabal update --verbose=3
ProxyChains-3.1 (http://proxychains.sf.net)
Downloading the latest package list from hackage.haskell.org
Sending:
GET /packages/archive/00-index.tar.gz HTTP/1.1
Host: hackage.haskell.org
User-Agent: cabal-install/1.16.0.2
Creating new connection to hackage.haskell.org
|DNS-request| hackage.haskell.org
|S-chain|-<>-127.0.0.1:7070-<><>-4.2.2.2:53-<><>-OK
|DNS-response| hackage.haskell.org is 88.198.224.242
Segmentation fault

Note: my proxychains works well with wget.

2) install Wheezy (7.2) using debootstrap, chroot to it, install haskell platform and
  proxychains, do cabal update
  with and without proxychains, same results : hang without proxychains, Segmentation fault
  with proxychains.

3) install Wheezy (7.2) using kvm, do same as 2), once again get same results.

So I guess there is something wrong in the network part of cabal-install.

Hi,

Am Sonntag, den 03.11.2013, 19:41 +0800 schrieb Zhang Zengbo:

unfortuately, I cannot reproduce it here. Is there anything special
about your network setup? E.g. forced proxies or something of the kind?

Greetings,
Joachim

HI Joachim and all,

I guess two situations may help to reproduce it:

1. I am behind two NATs, one is a home router, one is the connection point
from ISP to Internet (maybe more, depends on ISP).
2. The network speed is slow from my pc to hackage server (about 10KB/s)

And there is another phenomenon after I reported the bug: I tried again (3
times) to do cabal update, with two times get partial content (almost full,
let me say, only ~200k lost compared to a wget-ed and verified version but
I didn't record the number ) after about 10 minutes then it reported the
tarball is broken; and the last time it hangs with 3 hours so I did Ctrl-C
to exit (same as the bug report itself).  If you need I can do more times
and give some accurate data (time/size).

From the new phenomenon, I guess again it is about a weak design of tcp
itself: when there is only one direction of data flow, the sender may close
the tcp link more quickly than the receiver at certain condition: for some
point the sender lose all data packages (and re-transmissions) to the
receiver, and the receiver don't know it at all.  Although it is a tcp
weakness, AFAIK, this should be overcome by some upper layer protocol
implementation.

And another thing I am surprised is about proxychains, it is 100%
segmentation fault on my side. I just use a ssh dynamic port forwarding and
in wget case it can speed up the download to hackage server. It should be
easy to reproduce in my opinion.

Best,
Zengbo

2013/11/4 Joachim Breitner <nomeata@debian.org>

Dear Joachim and all mentainers:

   I have more information on this bug. When I changed ~/.cabal/config file
to use

  remote-repo: old.hackage.haskell.org:http://old.hackage.haskell.org/

instead of

  remote-repo: hackage.haskell.org:http://
hackage.haskell.org/packages/archive

cabal update successed; When I changed back to default, the issue is then
reproducable again.

In both case, proxychains cabal update will get segmentation fault.

Hope it helps.

Best,

Zengbo






2013/11/4 张增波 <zengbo.zhang@gmail.com>