14 Zombie Process Mode 3 4 supplement

The previous Process Control 2, describes the zombie process, and the solution of the two kinds of 4. Add two more below.

How to resolve:

3: Ignore SIGCHLD signal

Parent process settings Ignore SIGCHLD signal, child process end automatically frees process table resource

Ignore SIGCHLD signal:

Signal (SIGCHLD, sig_ign)

4: Capture SIGCHLD Signal

The parent process captures the SIGCHLD signal and executes the wait () in the Capture function code

Handling SIGCHLD Signals:

void Pfun (int nsignal)

Signal (Sigchil, Pfun)

Zombie Process:

void Testzomb ()

{

pid_t pid=fork ();

if (pid==0)

{

printf ("This is a child:%d\n", getpid ());

_exit (0);

}

Else

{

printf ("This is a parent:%d\n", getpid ());

while (1);

}

}

Rowe 3440 3110 23:04 pts/0 00:00:08./main

Rowe 3441 3440 0 23:04 pts/0 00:00:00 [main] <defunct>

The <defunct> description is a zombie process and cannot be terminated with the kill command, nor can it be manipulated.

Ignore SIGCHLD signal mode:

void Testzomb ()

{

pid_t pid=fork ();

if (pid==0)

{

printf ("This is a child:%d\n", getpid ());

_exit (0);

}

Else

{

Parent process ignores SIGCHLD

Signal (sigchld,sig_ign);

printf ("This is a parent:%d\n", getpid ());

while (1);

}

}

Capture SIGCHLD Signal mode:

void func (int sig)

{

printf ("Receive signal:%s[%d]\n", Strsignal (SIG), SIG);

Wait (NULL);

}

void Testzomb ()

{

pid_t pid=fork ();

if (pid==0)

{

printf ("This is a child:%d\n", getpid ());

_exit (0);

}

Else

{

The parent process handles the SIGCHLD

Signal (SIGCHLD,FUNC);

printf ("This is a parent:%d\n", getpid ());

while (1);

}

}

After wait ends, the process Resource table is freed by Init.

14 Zombie Process Mode 3 4 supplement