preforkserver.py 文件源码

def _spawnChild(self, sock):
        """
        Spawn a single child. Returns True if successful, False otherwise.
        """
        # This socket pair is used for very simple communication between
        # the parent and its children.
        parent, child = socket.socketpair()
        parent.setblocking(0)
        setCloseOnExec(parent)
        child.setblocking(0)
        setCloseOnExec(child)
        try:
            pid = os.fork()
        except OSError, e:
            if e[0] in (errno.EAGAIN, errno.ENOMEM):
                return False # Can't fork anymore.
            raise
        if not pid:
            # Child
            child.close()
            # Put child into its own process group.
            pid = os.getpid()
            os.setpgid(pid, pid)
            # Restore signal handlers.
            self._restoreSignalHandlers()
            # Close copies of child sockets.
            for f in [x['file'] for x in self._children.values()
                      if x['file'] is not None]:
                f.close()
            self._children = {}
            try:
                # Enter main loop.
                self._child(sock, parent)
            except KeyboardInterrupt:
                pass
            sys.exit(0)
        else:
            # Parent
            parent.close()
            d = self._children[pid] = {}
            d['file'] = child
            d['avail'] = True
            return True