Shell Programming and Scripting

i have quit a few process running in background. The problem is even though the process seems to run background. the process gets hanged or wait for something and these detail is not shown in their respective logs

How to check the status of a background process when it's
1) gets hanged
2) waiting for something

I know of a command called ps, but how to use it to know what i want. Plz help me in this ?
Also i have investigated in with command ps gv [Pid_Id] and it give me info like the below

PID TTY STAT TIME PGIN SIZE RSS LIM TSIZ TRS %CPU %MEM COMMAND

Does it have to do anything with memory when the process gets hanged/wating . please correct me if i m wrong

man page for ps:
If the process has memory problems it would bounce to the limits for memory set by the ulimits for the user that started the process.
Nevertheless you could check with vmstat easily if your box has memory problems overall.