Any reason why reading stdout should fail?

Stream: general

[Daniel Donnelly]

        elif self.state == self.AwaitingResponse:
            for line in self._proc.stdout:
               self.check_pause()
               json = JSON.loads(line)
               self.receive_queue.append(json)
            self.state = self.ProcessingResponse

This grabs the first few lines but on the last line the thread the above is running in crashes because of the read of stdout. No error is presented in my debugger.

I'm connecting the process like this:

  def connect_to_server(self):
      exec = self.lean_executable
      self._proc = subprocess.Popen([exec, "-j0", "--server"],
                                      stdin =subprocess.PIPE,
                                      stdout=subprocess.PIPE,
                                      stderr=subprocess.PIPE,
                                      universal_newlines=True,
                                      bufsize=1, env={'LEAN_PATH': self.lean_folder})
      self.state = self.ServerRunning

Also doing stdout.readlines() will crash the process as well as stdout.read() or stdout.readline()'ing to the end.

[Daniel Donnelly]

The solution is to use communicate():

            stdout, stderr = self._proc.communicate()
            print(stdout)

Process doesn't crash when you do that.