Cannot allocate memory: fork: Unable to fork new process?

I've face that problem either while hosting a java app with jenkins, mysql & tomcat on ubuntu on an vm of AWS.

First steps I used to solve the problem with restarting a vm.

AWS doesn't give swap memory on a harddrive by default, so you'd better to make it with your hands. How to do this you can find here. Need to mention: the solution with swap zone (have no idea why) haven't work for me, I had to create a swap file.

Good luck to you!

I had same problem to fix it there is 2 options:

1- move from micro instances to small and this was the change that solved the problem (micro instances on amazon tend to have large cpu steal time)

2- tune the mysql database server configuration and my apache configuration to use a lot less memory.

tuning guide for a low memory situation such as this one: http://www.narga.net/optimizing-apachephpmysql-low-memory-server/(But don't use the suggestion of MyISAM tables - horrible...)

this 2 options will make the problem much much less happening .. I am still looking for better solution to close the process that are done and kill the ones that hang in there .

Changed Apache's prefork MPM into the httpd.confThese are the values I ended up using:

StartServers 1

MinSpareServers 1

MaxSpareServers 5

ServerLimit 16

MaxClients 16

MaxRequestsPerChild 0

ListenBacklog 100

Then, try to desactivate some modules php with sudo a2dismod name_of_module