python - 信号处理程序退出，但程序继续运行？

Question

显然，当我的信号处理程序退出时，我的程序继续运行。甚至在“日志完成，立即关闭”之后引发的异常也证明了这一点。有人可以解释为什么会这样吗？注意功能已经简化

^Clog   Ctrl-C
backup  State: not_span 328, pos 22, all_cycles 19
backup  backup complete, you may force exit now
log     Done, close now
Traceback (most recent call last):
  File "singleEdger.py", line 219, in <module>
    mySingleEdger.outputAllCycles()
  File "singleEdger.py", line 141, in outputAllCycles
    r = self.returnCycle( self.dfs_tree, self.not_span[self.pos])
  File "singleEdger.py", line 72, in returnCycle
    udfs = nx.Graph(dfs)                    # The trick is to make it undirected
  File "/var/lib/python-support/python2.6/networkx/graph.py", line 86, in __init__
    convert.from_whatever(data,create_using=self)
  File "/var/lib/python-support/python2.6/networkx/convert.py", line 76, in from_whatever
    "Input is not a correct NetworkX graph."
networkx.exception.NetworkXError: Input is not a correct NetworkX graph.

这些是引用函数

    def sigHandler(self, arg1, arg2):
        out('log', 'Ctrl-C')
        self.backup()
        out('log', 'Done, close now')
        exit()


    def outputAllCycles(self):
        while self.pos < len(self.not_span):
            r = self.returnCycle( self.dfs_tree, self.not_span[self.pos])
            if r:
                self.all_cycles.append( r )
                for each in r:      # now it's [ (3,4), (5,6) ]
                    each = (sellHash(each[0]), sellHash( each[1]) )
                    self.outfo.write( each[0] +'\t'+ each[1] )
                    self.outfo.write( '\n')
                self.outfo.write( '\n')
            self.pos += 1
        out( "singleEdger", "outputAllCycles done")


    def backup(self):
        out( 'backup', 'State: not_span %i, pos %i, all_cycles %i' % ( len(self.not_span), self.pos, len(self.all_cycles)) )
        out( 'backup', 'backup complete, you may force exit now')

Answer 1

我不认为你的代码还在运行。尽管它在代码中的位置，但不能保证异常输出出现在最终打印消息之前。异常输出将转到 STDERR，但您的打印语句将转到 STDOUT；在此示例中，两者都恰好写入同一终端设备。两者是独立缓冲的，所以输出的顺序不是强制的；也就是说，您无法从输出的相对位置推断出任何信息。

如果将打印语句放入单元测试中，您可以在单元测试框架中看到相同的现象。