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Posted to users@httpd.apache.org by Richard Crawford <rc...@unexmail.ucdavis.edu> on 2005/03/09 19:31:21 UTC
[users@httpd] Delivering huge documents
We're having a problem delivering very large pdf documents to our
website users. I'm not sure that this is something I can address in the
httpd configuration, but I've toyed with the TimeOut directive in
httpd.conf. Am I on the right track?
--
Richard S. Crawford
Programmer III
UC Davis Extension Distance Education Group (http://unexdlc.ucdavis.edu)
2901 K Street, Suite 200C
Sacramento, CA 95816
(916)327-7793
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[users@httpd] Problem with mod_disk_cache - anyone seen this?
Posted by Steve Waddington <st...@exetel.com.au>.
I have noticed a problem using mod_disk_cache (any 2.0 release afaik).
When the server date is changed from its current date to an earlier date web
pages will display as raw html on non IE browsers.
For example, a web server I am running lost sync with its ntp server and its
date was running fast by two hours. I resynced it with the ntp server, so
its local time was now two hours earlier. Any web page that had been cached
by mod_disk_cache, now had a cache time stamp two hours _later_ than the
system time.
When those pages were viewed by a non IE browser such as Firefox or Mozilla,
the browser displayed raw html code in clear text. It seems the mime type
was not understood. All the pages looked fine in IE however.
>From the search I did for possible causes, it seems some folk have reported
similar problems, but there is no diagnosis for this case.
My initial work around was to stop ntpd and advance the system date three
hours - which fixed the browser display problem.
To fix the problem fully I disabled mod_disk_cache set the date to the
correct time, then restarted httpd. I think if I enable mod_disk_cache and
reload after the system date has passed the cached page time stamp, it
should be ok - can anyone confirm if that will be the case? It is a
production server with 70 sites hosted, so I am not keen to experiment to
see if it works or not.
Another possible solution would have been to set the system date to the
correct time and then delete all the /var/cache/httpd content, forcing it to
be recreated with the correct time stamps. But I am not sure of the
repercussions of doing that, does anyone know?
Regards,
Steve
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Re: [users@httpd] Delivering huge documents
Posted by Stuart Low <st...@serverpeak.com>.
> > We have a document which is a 1.5MB PDF document. For some of our
> > visitors, the download seems to stop before the full document is
> > delivered. I haven't been able to identify any common issues among the
> > visitors who are having the problems (though I suspect they're on a
> > dialup connection). The PDF itself seems to be have no problems, since
> > it's delivered just fine over broadband connections. This issue appears
> > to be browser-independent as well. I've also confirmed that the
> > affected users are using the most recent version of Acrobat Reader as well.
Just a random suggestion. Do you have mod_gzip compression enabled on
your Apache install? We had the same problem and ended up having to add
a manual whitelist so that .pdf wasn't gzip compressed.
Stuart
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Re: [users@httpd] Delivering huge documents
Posted by Noah <si...@onastick.net>.
On Wed, Mar 09, 2005 at 11:02:28AM -0800, Richard Crawford wrote:
> We have a document which is a 1.5MB PDF document. For some of our
> visitors, the download seems to stop before the full document is
> delivered. I haven't been able to identify any common issues among the
> visitors who are having the problems (though I suspect they're on a
> dialup connection). The PDF itself seems to be have no problems, since
> it's delivered just fine over broadband connections. This issue appears
> to be browser-independent as well. I've also confirmed that the
> affected users are using the most recent version of Acrobat Reader as well.
My first suggestion is to look at your network and rule out the obvious;
problems with large file transfers are often caused by duplex
mismatches. Check your upstream switch stats for collisions on the port
your host is on. Linux's 'ifconfig' will also show you collisions (if
you're on linux). I'd expect the issue to affect all downloads of the
large file, but it's still good to rule out the easy stuff. =)
Does this affect other protocols as well? For instance, transferring large
files over FTP? Trying running an FTP server on the same box and serve the
same file to a client machine that exhibits this behavior. If the same thing
happens, it's not an application issue, so you get to start poking at things
from a network perspective. Does the transfer just stop dead, or does it slow
down over time and /then/ stop? In either case, you may should consider finding
a client that exhibits this behavior, sniffing the packets with tcpdump. Something
like:
tcpdump -s 1500 -w sniff.pcap port 80 and host $remote_ip
...where $remote_ip is the IP of the client.
Poke at the resulting file in ethereal (with TCP sequence analysis
on; Edit->Preferences->Protocols->TCP) and see if you're
restransmitting packets. You may also want to check out TCPTrace
(http://www.tcptrace.org/).
--n
--
<huey> dd of=/dev/fd0 if=/dev/flippy bs=1024
<huey> ^^^ Making Flippy Floppy
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Re: [users@httpd] Delivering huge documents
Posted by Richard Crawford <rc...@unexmail.ucdavis.edu>.
Noah wrote:
> On Wed, Mar 09, 2005 at 10:31:21AM -0800, Richard Crawford wrote:
>
>>We're having a problem delivering very large pdf documents to our
>>website users. I'm not sure that this is something I can address in the
>>httpd configuration, but I've toyed with the TimeOut directive in
>>httpd.conf. Am I on the right track?
>
>
> What exactly is the problem and what (if any) effect is this having on
> Apache? =)
Sorry I wasn't clear. Got interrupted and sent the earlier message off
in a hurry.
We have a document which is a 1.5MB PDF document. For some of our
visitors, the download seems to stop before the full document is
delivered. I haven't been able to identify any common issues among the
visitors who are having the problems (though I suspect they're on a
dialup connection). The PDF itself seems to be have no problems, since
it's delivered just fine over broadband connections. This issue appears
to be browser-independent as well. I've also confirmed that the
affected users are using the most recent version of Acrobat Reader as well.
I had wondered if the TimeOut directive in my Apache httpd configuration
might be the culprit; I knew that in earlier versions, if a document was
too large, the TimeOut directive could cause Apache to stop delivering
huge documents if it took longer than the amount of time defined in
TimeOut. However, we're using Apache 2.0.45, and our TimeOut is set to
twenty minutes. Just to be on the super-safe side, I set the TimeOut to
two hours, though doing that makes me twitch.
Since we're using Cold Fusion, I also double-checked our timeout
configuration in Cold Fusion. It is disabled, as I set it up to be; I
enabled it and set it to twenty minutes, but I don't think this will
make a difference.
So, this is annoying me and it's costing us customers. I've also set my
KeepAliveTimout setting pretty high, but I don't know if that will have
an impact.
So, any suggestions would be greatly appreciated.
--
Richard S. Crawford
Programmer III
UC Davis Extension Distance Education Group (http://unexdlc.ucdavis.edu)
2901 K Street, Suite 200C
Sacramento, CA 95816
(916)327-7793
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Re: [users@httpd] Delivering huge documents
Posted by Noah <si...@onastick.net>.
On Wed, Mar 09, 2005 at 10:31:21AM -0800, Richard Crawford wrote:
> We're having a problem delivering very large pdf documents to our
> website users. I'm not sure that this is something I can address in the
> httpd configuration, but I've toyed with the TimeOut directive in
> httpd.conf. Am I on the right track?
What exactly is the problem and what (if any) effect is this having on
Apache? =)
--n
--
<huey> dd of=/dev/fd0 if=/dev/flippy bs=1024
<huey> ^^^ Making Flippy Floppy
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