To prevent Zombie

[uma_iyer]

Hi All,

What are the different ways to prevent zombie?
I am totally confused about using:
a) wait system call
b) waitpid system call
c) using signals - signal handler for SIGCHLD with SIG_IGN and sigaction system call

for handling zombies ???

thanx

[hazel]

Wait and waitpid do the same thing: they wait until a child terminates and then collect its exit information. Wait waits until any child terminates, waitpid does it for the child with the specified PID. This is default behaviour; you can set a NOHANG flag so that the process doesn't actually wait but only checks if a child has terminated and then returns.

The process also gets a SIGCHILD when a child dies and can act on it but I don't think there is any way of collecting the exit information of the child except by way of wait/waitpid and, without this information being collected, the child will become a zombie.