SSH and -bash: fork: Cannot allocate memory VPS Ubuntu
Seems you have run out of memory. Many VPS servers are setup with no swap, so when you run out of memory, it will kill things off in a seemingly random manner.
The easiest way to fix it is to get more memory provisioned to your VPS, likely costing more money. The next best way (other than running less stuff and memory optimizing everything running) would be to add a swap partition or swap file.
For a 1GB swap file (as root):
dd if=/dev/zero of=/swapfile bs=1M count=1024mkswap /swapfileswapon /swapfileBe sure to add it to /etc/fstab too as:
/swapfile none swap defaults 0 0That will make it come back after reboot.
To get out of this condition without rebooting, you can trigger the OOM killer manually as follows:
echo 1 > /proc/sys/kernel/sysrqecho f > /proc/sysrq-triggerecho 0 > /proc/sys/kernel/sysrqHaving done so you can inspect dmesg to find the process responsible for taking all your memory.