After configuring a RHEL6 box with MQ 7.0.1.5 we hit a problem where by when we had a large number of connections (118) it would then fail to allow any more connections. You could also not perform any operations on the box. If you attempted to make a change you got the following error

• fork: retry: Resource temporarily unavailable

After lots of searching this was fixed by doing the following

Disabling SELinux

• setenforce Permissive
• reboot

Changing the users file limitations. Go to /etc/security/limits.conf, change this user’s limitation:

username         hard    nproc         unlimited
username         soft    nproc           unlimited

After making these changes we were able to make many more client connections