python2.7的paramiko模块下载大文件失败 编程中需要用到 Python（2.7） 的 paramiko 模块下载服务器上面一个比较大的文件，命令如下：client = paramiko.Transport(ip, port) client.connect(username=user, password=password) sftp = paramiko.SFTPClient.from_transport(client) sftp.get(remotefile, localfile)发现一个很奇怪的现象，下载比较小的文件时，没有发现异常，直到有一次下载一个 300mb+的文件时，中途卡住一直下载不下来解决方案：修改 python 有关 sftp 数据下载的源码，文件位置为：/usr/lib/python2.7/site-packages/paramiko/sftp_file.py找到_prefetch_thread 函数：def _prefetch_thread(self, chunks): # do these read requests in a temporary thread because there may be # a lot of them, so it may block. for offset, length in chunks: num = self.sftp._async_request( self, CMD_READ, self.handle, long(offset), int(length)) with self._prefetch_lock: self._prefetch_extents[num] = (offset, length)代码作者注释说明了此处可能存在并发过大的问题，所以我们对他进行修改：def _prefetch_thread(self, chunks): # do these read requests in a temporary thread because there may be # a lot of them, so it may block. max_request_num = 512 to_wait = False for offset, length in chunks: num = self.sftp._async_request( self, CMD_READ, self.handle, long(offset), int(length) ) with self._prefetch_lock: self._prefetch_extents[num] = (offset, length) if len(self._prefetch_extents) >= max_request_num: to_wait = True if to_wait: time.sleep(1) to_wait = False总体思路就是限制同时存在的异步请求总数