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I am experiencing some odd behavior with apache. I have requests that are hanging for exactly two minutes. The request could be one file one time, and then a completely different file another time.

Here are a couple of screenshots of my network inspector.

ss #1 original URL: http://tiny-img.com/image.php?di=QNKO

ss #2 original URL: http://tiny-img.com/image.php?di=3BFS

ss #3 original URL: http://tiny-img.com/image.php?di=49VN

I'm not sure how to troubleshoot this, there are no errors in the logs, and I'm not finding anything referring to similar issues on the web.

Any ideas on how I can troubleshoot this, and/or if you know what is going on, I would appreciate any insight to what I can do to correct this.

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Depending on how busy the webserver is you could restart httpd via a strace that follows spawned children (via -f) that would give you more of an indication of what it's trying to do when it hangs (including whether it's waiting on a locked resource to become available, or waiting on a network response). It's probably some sort of a high latency network resource or some sort of QoS control. –  Joel Davis Oct 2 '13 at 0:50
    
Also, it looks like these are screencaps from Chrome's developer tools feature. You may try to enable nscd locally and see if that avoids this issue. –  Joel Davis Oct 2 '13 at 1:02
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1 Answer 1

up vote 5 down vote accepted

Delays like this are often caused by reverse DNS lookups (i.e. resolving an IP address to a hostname).

Do you have HostNameLookups turned on in the apache config? If so, turn it off.

See also http://serverfault.com/questions/100225/apache-httpd-wont-stop-doing-reverse-dns-requests-for-clients-ips for other tips on disabling hostname resolution in apache.

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2  
Agreed. 2 minutes screams DNS issues. –  Aaron D. Marasco Oct 2 '13 at 0:43
    
fwiw, it probably is DNS but it could be DNS on the client side as well, especially if the OP is on a weak WiFi connection or something like that. nscd is probably a good choice as well (even if only as a troubleshooting tool). Just thought I'd add that to the mix. –  Joel Davis Oct 2 '13 at 2:42
    
true enough, but if it is client-side, there's not much you can do on the server to solve that. –  cas Oct 2 '13 at 5:02
    
No but it does let the OP know that he doesn't have anything to worry about and it's just that his test that's flawed. –  Joel Davis Oct 2 '13 at 12:32
    
I have HostNameLookups turned off, so its not that, any other ideas? –  Jeffrey L. Roberts Oct 3 '13 at 23:09
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