为什么我的Protobuf消息仅在从Windows机箱发送到Linux机箱时被截断？

Question

我正在使用一个普通的,简单的,同步的Python服务器和客户端组合来通过TCP连接发送Google Protobuf消息.服务器使用Python 2.5.4和Google Protobuf 2.4.1在Windows XP上运行.客户端使用Python 2.7.3和Google Protobuf 2.4.1在Ubuntu 12.04服务器上运行.

当我在XP机器上运行服务器并尝试使用Ubuntu机器上的客户端与它通信时,服务器正好解析请求消息并发送响应消息就好了,但客户端遇到google.protobuf.message.DecodeError: Truncated message错误.

如果我在XP机器上运行客户端和服务器,我没有遇到错误,如果我在Ubuntu机器和XP机器上的客户端上运行服务器,也不会遇到错误.

看起来它可能与实际的Protobuf消息本身有关...如果我使用一个非常简单的Protobuf消息,如下例中的那个,事情似乎工作正常.但是,一旦我开始使用我们在生产中使用的实际Protobuf消息,我就会看到错误.虽然我只是在Windows上的服务器和Ubuntu上的客户端时才会收到错误,但这看起来仍然很奇怪.

可能会发生什么想法？!考虑到一些环境限制,我必须在Windows机器和Google Protobuf 2.4.1上坚持使用Python 2.5.

示例protobuf.proto

message Foo {
  required string name = 1;
}

message Bar {
  required string name = 1;
}

message Sucka {
  required string name = 1;
  repeated Foo    foos = 2;
  repeated Bar    bars = 3;
}

message Result {
  enum Exception {
    NONE    = 0;
    GENERIC = 1;
  }

  required Exception exception = 1;
  optional string    message   = 2;
  optional Sucka     sucka     = 3;
}

server.py

import signal, socket, struct

from protobuf import Sucka, Result

class TestServer():
  def __init__(self, host = '0.0.0.0', port = 9989):
    self.host = host
    self.port = port

    self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    self.socket.bind((self.host, self.port))
    self.socket.listen(1)

    self.running = False
    self.conn    = None

    self.run()

  def run(self):
    def handle_exit(signum, stack):
      print 'Shutting down server in response to signal %s' % (str(signum))
      self.running = False

    signal.signal(signal.SIGINT,  handle_exit)
    signal.signal(signal.SIGTERM, handle_exit)

    print 'Waiting on a connection'
    self.running = True

    while self.running:
      try:
        self.conn, addr = self.socket.accept()

        print 'Connection from:', addr

        size_t = self.conn.recv(4)
        size   = struct.unpack('!I', size_t)
        data   = self.conn.recv(size[0])

        if not data:
          raise Exception('No data... did the client close the connection?')

        result = Result()

        try:
          sucka = Sucka()
          sucka.ParseFromString(data)

          result.exception = result.NONE
          result.sucka.CopyFrom(sucka)
        except Exception, ex:
          print str(ex)
          result.exception = result.GENERIC
          result.message   = 'Exception: %s' % (str(ex))
        finally:
          if self.conn: self.conn.close()

    self.socket.close()

if __name__ == '__main__':
  s = TestServer()

client.py

import socket, struct, time

from protobuf import Sucka, Result

class TestClient():
  def __init__(self, sucka, host = '127.0.0.1', port = 9989):
    self.addr = (host, port)
    self.__call(sucka)

  def __call(self, sucka):
    size   = sucka.ByteSize()
    size_t = struct.pack('!I', size)

    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    sock.connect(self.addr)
    sock.send(size_t)
    sock.send(sucka.SerializeToString())

    size_t = sock.recv(4)
    size   = struct.unpack('!I', size_t)
    data   = sock.recv(size[0])

    result = Result()
    result.ParseFromString(data)

    if result.exception != Result.NONE:
      raise Exception(result.message)

    print str(result.sucka)

if __name__ == '__main__':
  import sys, os
  sys.path.insert(0, os.path.abspath(os.path.dirname(__file__)))

  from protobuf import Sucka

  sucka      = Sucka()
  sucka.name = 'testing'

  for i in range(0, 25):
    foo      = sucka.foos.add()
    foo.name = 'foo-%i-tester' % i

  for i in range(0, 25):
    bar      = sucka.bars.add()
    bar.name = 'bar-%i-tester' % i

  c = TestClient(sucka, '127.0.0.1', 9989)