Limitations
The maximum value for those fields are integer
values.
The number of processes is limited by the kernel, to roughly 25.000 to 50.000
What happens when you set ridiculous high values?
Depending on other amouont of traffic, you might be happy with the server for hours, weeks, or months. After a time, the server will probably get unresponsive.
The exact behaviour highly depends on many factors and might be totally unpredictable.
What should you do?
There are basic direction towards what the settings should go, like spawning around cores*2 (think hyperthreading) processes and so on.
The suggested values are just an orientation, not an advice that fits all needs.
The settings highly depend on your code. How much memory does it use, how much cpu time, how much memory leaking, ...
522 Connection timeout
Various issues can lead to a connection timeoout. Your PHP application might
- experience fatal errors (seg faults)
- might have run into infinite loops
- might itself be waiting on locks or responses
- bad configured network / firewall.
Try to use a debugger on your code and watch the error log closely.