When I tested myself, I would see intermittent failures, and Firebug would show that either the response length was zero, or the connection seemed to fail completely. Application logs on the server showed no problems, including when Firebug reported the response was empty -- the application log on the server showed data had been sent.
On a hunch I fired up apachebench (
ab) and was surprised to find some connection failures:
[jnet@Stan ~]$ ab -v 1 -n 1000 -c 10 $url This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking workingman.smart-safe-secure.com (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Completed 600 requests Completed 700 requests Completed 800 requests Completed 900 requests Completed 1000 requests Finished 1000 requests Server Software: Apache/2.2.3 Server Hostname: workingman.smart-safe-secure.com Server Port: 443 SSL/TLS Protocol: TLSv1/SSLv3,DHE-RSA-AES256-SHA,1024,256 Document Path: / Document Length: 659 bytes Concurrency Level: 10 Time taken for tests: 104.086 seconds Complete requests: 1000 Failed requests: 2 (Connect: 2, Receive: 0, Length: 0, Exceptions: 0) Write errors: 0 Total transferred: 945000 bytes HTML transferred: 659000 bytes Requests per second: 9.61 [#/sec] (mean) Time per request: 1040.855 [ms] (mean) Time per request: 104.086 [ms] (mean, across all concurrent requests) Transfer rate: 8.87 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 356 844 215.7 840 2268 Processing: 68 194 138.9 128 1483 Waiting: 67 178 122.0 116 1426 Total: 494 1039 241.8 993 2623 Percentage of the requests served within a certain time (ms) 50% 993 66% 1039 75% 1101 80% 1162 90% 1407 95% 1492 98% 1626 99% 1718 100% 2623 (longest request)
These requests were for a static HTML page, so my PHP application doesn't seem to be the issue here.
Running the tests over normal HTTP (non-ssl) produced no failures at all. I am at a loss as to what could be happening... not even sure how to troubleshoot from here. I will gladly post httpd.conf configuration, just let me know what parts would help. Server is Apache/2.2.3 (CentOS), with mpm_worker and mod_fastcgi...
UPDATE: I just had my first ab test return 2 connection failures over normal HTTP, for the same HTML page. So it looks like SSL isn't the problem after all...
UPDATE 2: It's possible this is some sort of network issue, because I am not able to replicate this using
ab on a server in the same data center, nor am I able to replicate this using
ab on localhost. However pinging the server in question from my workstation shows 0% packet loss... So I am unsure of what steps to take next.
UPDATE 3: In case it helps, if I run
ab to benchmark over an SSH tunnel, I get no failures... so maybe this is a networking issue instead of an apache issue...