name : popen_forkserver.py import io import os from .context import reduction, set_spawning_popen if not reduction.HAVE_SEND_HANDLE: raise ImportError('No support for sending fds between processes') from . import forkserver from . import popen_fork from . import spawn from . import util __all__ = ['Popen'] # # Wrapper for an fd used while launching a process # class _DupFd(object): def __init__(self, ind): self.ind = ind def detach(self): return forkserver.get_inherited_fds()[self.ind] # # Start child process using a server process # class Popen(popen_fork.Popen): method = 'forkserver' DupFd = _DupFd def __init__(self, process_obj): self._fds = [] super().__init__(process_obj) def duplicate_for_child(self, fd): self._fds.append(fd) return len(self._fds) - 1 def _launch(self, process_obj): prep_data = spawn.get_preparation_data(process_obj._name) buf = io.BytesIO() set_spawning_popen(self) try: reduction.dump(prep_data, buf) reduction.dump(process_obj, buf) finally: set_spawning_popen(None) self.sentinel, w = forkserver.connect_to_new_process(self._fds) # Keep a duplicate of the data pipe's write end as a sentinel of the # parent process used by the child process. _parent_w = os.dup(w) self.finalizer = util.Finalize(self, util.close_fds, (_parent_w, self.sentinel)) with open(w, 'wb', closefd=True) as f: f.write(buf.getbuffer()) self.pid = forkserver.read_signed(self.sentinel) def poll(self, flag=os.WNOHANG): if self.returncode is None: from multiprocessing.connection import wait timeout = 0 if flag == os.WNOHANG else None if not wait([self.sentinel], timeout): return None try: self.returncode = forkserver.read_signed(self.sentinel) except (OSError, EOFError): # This should not happen usually, but perhaps the forkserver # process itself got killed self.returncode = 255 return self.returncode