environment/lib/python2.7/site-packages/IPython/parallel/controller/scheduler.py
def fail_unreachable(self, msg_id, why=error.ImpossibleDependency):
        """a task has become unreachable, send a reply with an ImpossibleDependency
        error."""
        if msg_id not in self.depending:
            self.log.error("msg %r already failed!", msg_id)
            return
        job = self.depending.pop(msg_id)
        for mid in job.dependents:
            if mid in self.graph:
                self.graph[mid].remove(msg_id)

        try:
            raise why()
        except:
            content = error.wrap_exception()

        self.all_done.add(msg_id)
        self.all_failed.add(msg_id)

        msg = self.session.send(self.client_stream, 'apply_reply', content,
                                                parent=job.header, ident=job.idents)
        self.session.send(self.mon_stream, msg, ident=[b'outtask']+job.idents)

        self.update_graph(msg_id, success=False)
def fail_unreachable(self, msg_id, why=error.ImpossibleDependency):
        """a task has become unreachable, send a reply with an ImpossibleDependency
        error."""
        if msg_id not in self.depending:
            self.log.error("msg %r already failed!", msg_id)
            return
        job = self.depending.pop(msg_id)
        for mid in job.dependents:
            if mid in self.graph:
                self.graph[mid].remove(msg_id)

        try:
            raise why()
        except:
            content = error.wrap_exception()

        self.all_done.add(msg_id)
        self.all_failed.add(msg_id)

        msg = self.session.send(self.client_stream, 'apply_reply', content,
                                                parent=job.header, ident=job.idents)
        self.session.send(self.mon_stream, msg, ident=[b'outtask']+job.idents)

        self.update_graph(msg_id, success=False)
a task has become unreachable, send a reply with an ImpossibleDependency
        error.