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Re: Weird Apache problem, hanging on particular data patterns



On 10/24/06, vashts <vashts@gmail.com> wrote:
And to reiterate... I can move the files around to different drives
and filesystems. They still have the problem.

I have checked ALL filesystems.

The transfer does seem to strangely work via Apache when done through
localhost. Yet not onto machines off of even the same switch.

I have succesfully split one of the files up into smaller chunks and
reassembled (the file is fine).

I can retreive the file without any corruption,  with vsftpd or
scp/sftp. Md5sum stays the same as it's always been (Again the file is
fine).

It is not an issue with my network connection. All but two particular
files so far I've run into transfer fine at the speed they should go
with 1000baseT (about 40mBYTES/sec locally and 10mBYTES/sec if I'm
lucky from some public ftp sites, and usually around 5mBYTES/sec from
umn.edu's debian mirror). Size of the files doesn't seem to matter
whatsoever. Also there are ZERO errors being reported by the switch
for the port that machine is connected to, also nothing in ipconfig as
far as errors. (My network is fine)

When I split one of the two "weird" files up into 1k chunks only the
second piece hangs when downloaded via apache, but every single other
piece is fine. This file when assembled hangs at exactly 1,130bytes,
so that makes perfect sense.



On 10/24/06, vashts <vashts@gmail.com> wrote:
> I already did. Nothing weird in dmesg. I also checked the filesystems
> thoroughly. Read what I said. :)
>
> On 10/24/06, Matus UHLAR - fantomas <uhlar@fantomas.sk> wrote:
> > On 23.10.06 10:00, Timothy Timmons wrote:
> > > Certain files, with seemingly no obvious correlation lock shortly
> > > after the transfer starts, usually within the first few k. I can move
> > > the file to a different drive/partition, rename it, and it doesn't
> > > matter. I can take a different file and it works just fine.
> > >
> > > I split one of the files that hangs up into 1k chunks and tried
> > > downloading each seperately. Only the second 1k chunk froze.
> > >
> > > The same thing seems to happen with some other programs, IRC DCC
> > > transfers for example.
> > >
> > > However, it works just FINE with VSFTPD or SCP/SFTP.
> > >
> > > I'm thinking some change in some library that Apache and some other
> > > programs use has some bug, but I am no expert here. I can send the 1k
> > > chunk(s) it is hanging on if this will help.
> > >
> > > This is REALLY weirding me out and everyone I know...
> > >
> > > Thanks in advance for any help!
> > >
> > > PS. A little more info: I've only found two files where I see this
> > > behavior. One hangs at exactly 1,130bytes, the other at 16,184,800
> > > bytes. I don't have the problem when I transfer from localhost. It
> > > doesn't seem to be any sort of LAN issue though. I'm getting the
> > > throughput I should, and no errors are showing up in ifconfig or on the
> > > switch it's plugged into.
> >
> > check 'dmesg' if the files aren't on broken part of your disk
> > --
> > Matus UHLAR - fantomas, uhlar@fantomas.sk ; http://www.fantomas.sk/
> > Warning: I wish NOT to receive e-mail advertising to this address.
> > Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
> > Emacs is a complicated operating system without good text editor.
> >
> >
> > --
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> >
> >
>


I just realized something. The machines I was testing the transfers
from aren't even in the same office. I thought they were, because the
transfer speeds were so high. If I do grab those files from a machine
on the same LAN they work fine. It only seems to happen when routed
over one of our WAN links, and only with those two files. I can only
conclude it's something with that upstream provider... but I wonder
how they could be doing any sort of application layer filtering while
not bogging their network down.?. I can nearly max that 100mbit link
when doing test ftps from some public ftp sites.

Sorry for the trouble.. I can't conclude it's anything else but that
provider anymore.. If the file is encrypted or otherwise obfuscated it
works fine. If I use SSL ftp it works fine... same goes for SCP/SFTP.



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