socket question:socket.error:(4,'Interrupted system call')

[Donn Cave]

Quoth =?gb2312?B?1cXJ2bPb?= <zhangsc at neusoft.com>:

| I have compiled a program to deal with Zombie process which caused by child process,it follows:
| ...
| ipsock=socket.socket(socket.AF_INET,10,8)
| while 1:
|   recvpack=ipsock.recv(1024)
|   ...
|   def sig_chld(signum, frame):
|   os.waitpid(-1,os.WNOHANG);
|   signal.signal(signal.SIGCHLD,sig_chld);
|   ret=os.fork()
|   if ret==0: #child process
|      .....
|
| It raise a error:
| Traceback (most recent call last):
|   File "d88.py", line 26, in ?
|     recvpack=ipsock.recv(1024)
| socket.error: (4, 'Interrupted system call')
|
| Why is error? How to correct it? Any ideas will be appreciated.

You asked for SIGCHLD, it arrived during recv() and interrupted it.

This would happen with C just as it would in Python.  In C it might
be worth your while to deal with it, but Python is so awkward with
signals anyway that in my opinion it's better to avoid them - no
signals.

I'm not sure I understand how the sig_chld handler fits into your
application, but if possible, I would simply call waitpid() at some
convenient interval to reap zombie processes.

	Donn Cave, donn at drizzle.com