test_subprocess.py 文件源码

def test_no_leaking(self):
        # Make sure we leak no resources
        if not mswindows:
            max_handles = 1026 # too much for most UNIX systems
        else:
            max_handles = 2050 # too much for (at least some) Windows setups
        handles = []
        try:
            for i in range(max_handles):
                try:
                    handles.append(os.open(test_support.TESTFN,
                                           os.O_WRONLY | os.O_CREAT))
                except OSError as e:
                    if e.errno != errno.EMFILE:
                        raise
                    break
            else:
                self.skipTest("failed to reach the file descriptor limit "
                    "(tried %d)" % max_handles)
            # Close a couple of them (should be enough for a subprocess)
            for i in range(10):
                os.close(handles.pop())
            # Loop creating some subprocesses. If one of them leaks some fds,
            # the next loop iteration will fail by reaching the max fd limit.
            for i in range(15):
                p = subprocess.Popen([sys.executable, "-c",
                                      "import sys;"
                                      "sys.stdout.write(sys.stdin.read())"],
                                     stdin=subprocess.PIPE,
                                     stdout=subprocess.PIPE,
                                     stderr=subprocess.PIPE)
                data = p.communicate(b"lime")[0]
                self.assertEqual(data, b"lime")
        finally:
            for h in handles:
                os.close(h)
            test_support.unlink(test_support.TESTFN)