Yes, in case you've noticed the site down... this would be the reason.

Robot Attack ! - well not the cool robot like the picture .. but a internet robot.  Some internet robots are good, and well behaved.  Search engines send out web-crawlers bots which slurp up data to be indexed.

They do it in reasonable bites (bytes).  

BUT THERE ARE EVIL ROBOTS - Ones which spawn a bajillion threads and try to download entire site in smallest amount of time possible.

On our little mrl site - it can quickly get overwhelmed with the horde of evil robots.

Here you can see a very very small snippet of the web server log

144.76.71.140 - - [04/Feb/2014:20:50:58 +0000] "GET /content/chatting-houston HTTP/1.1" 503 2612 "-" "Mozilla/5.0 (compatible; SISTRIX Crawler; http://crawler.sistrix.net/)"
144.76.71.140 - - [04/Feb/2014:20:51:11 +0000] "GET /content/some-pics-initial-prints HTTP/1.1" 503 2612 "-" "Mozilla/5.0 (compatible; SISTRIX Crawler; http://crawler.sistrix.net/)"
144.76.71.140 - - [04/Feb/2014:20:51:00 +0000] "GET /service/thingspeak HTTP/1.1" 503 2612 "-" "Mozilla/5.0 (compatible; SISTRIX Crawler; http://crawler.sistrix.net/)"
144.76.71.140 - - [04/Feb/2014:20:54:02 +0000] "GET /service/PointCloud HTTP/1.1" 503 2612 "-" "Mozilla/5.0 (compatible; SISTRIX Crawler; http://crawler.sistrix.net/)"
144.76.71.140 - - [04/Feb/2014:20:53:55 +0000] "GET /service/GUIService HTTP/1.1" 503 2612 "-" "Mozilla/5.0 (compatible; SISTRIX Crawler; http://crawler.sistrix.net/)"
144.76.71.140 - - [04/Feb/2014:20:54:23 +0000] "GET /service/Motor HTTP/1.1" 503 2612 "-" "Mozilla/5.0 (compatible; SISTRIX Crawler; http://crawler.sistrix.net/)"
144.76.71.140 - - [04/Feb/2014:20:54:13 +0000] "GET /blog/68 HTTP/1.1" 503 2612 "-" "Mozilla/5.0 (compatible; SISTRIX Crawler; http://crawler.sistrix.net/)"
144.76.71.140 - - [04/Feb/2014:20:51:31 +0000] "GET /content/easy-opencv-246-here-we-come HTTP/1.1" 503 2612 "-" "Mozilla/5.0 (compatible; SISTRIX Crawler; http://crawler.sistrix.net/)"
 
And here you can see the result....
 
[972354.298759] [ 8263]    48  8263   116099      319   0       0             0 httpd
[972354.298768] Out of memory: Kill process 30182 (httpd) score 25 or sacrifice child
[972354.298775] Killed process 30182 (httpd) total-vm:498932kB, anon-rss:3848kB, file-rss:80kB
 
That is the operating system saying.. HEY WEBSERVER YOU GOT WAY TOO MUCH MEMORY - YOU WILL BE KILLED !
 
Nooooooooo................. And then silence..............................