I've got a website (mobile web) running by 50 percent server and 1 balancer with haproxy, OS ubuntu 10.10

Apache Designs:

Timeout 300
KeepAlive On
MaxKeepAliveRequests 100
KeepAliveTimeout 15

StartServers          5
MinSpareServers       5
MaxSpareServers      10
MaxClients          150
MaxRequestsPerChild   0

The website is running well but all of a sudden now frequently it return blank page HTTP 500 (20 bytes in 30-50ms) without any error messages, however when i refresh it made correctly.

does anybody possess a clue on where it possibly goes completely wrong?

Update:

I have no idea if the relevance but anytime it couldn't be loaded browsers push me to download this content, so when i checked the downloaded file (title: Random_Chars.~.part) i discovered that within the header from the HTML these codes added by browser


meta http-equiv="Content-Type" content="text/html charset=utf-8"

meta title="viewport" content="width = device-width, maximum-scale = 1., initial-scale = 1."

meta title="apple-mobile-web-application-capable" content="yes"

--- ADDED BY BROWSER --

link href="styles/totally reset.css" rel="stylesheet" type="text/css"

link href="styles/base.css" rel="stylesheet" type="text/css"

script type="text/javascript" src="scripts/templates.js"

script type="text/javascript"

function init() Opera/3.0a1 Tablet browser .3.7", "styles/tweaks/maemo.css")

myStyleTweaks.add("Opera Small/4", "styles/tweaks/operamini.css")

myStyleTweaks.tweak()



addEvent("onload",init)

/script

In Apache Error Logs i discovered this line:


[client ip] File doesn't exist: /var/www/http:, referer: http://domain.com/search

note file filename "http:"

its sometimes not response 500 but 200 OK however the submissions are blank until i refresh couple of occasions Any assistance will be appreciated.

Look into the error log of the server, it might contain useful error messages. Be sure to enable logging (PHP's log_errors=1 phpSettings.log_errors=one in ZF config).

The script apparently crashes before getting an opportunity to set this content-Type header, therefore the browser don't known what related to the response, which is the reason why you visit a download dialog.

Sorry I discovered which was APC Module triggered that, i disable APC then individuals strange errors gone.