Question

os.waitpid文档https://docs.python.org/2.7/library/os.html#os.WNOHANG表示如果子进程尚未退出，则返回值为(0,0)但是FreeBSD（FreeBSD 10.3-RELEASE-p7）有时为{{1} }}或(0,-512)被返回。示例程序：

(0,-2048)

在osx（Python 2.7.11）和ubuntu（Python 2.7.6）上更正输出（类似/相同）

#!/usr/bin/env python

import os
import sys
import time

def show_waitpid_results(results):
    print("results: %s" % (str(results)))
    print("core: %r continued: %r stopped: %r signaled: %r exited %r" %
        (
            os.WCOREDUMP(results[1]),
            os.WIFCONTINUED(results[1]),
            os.WIFSTOPPED(results[1]),
            os.WIFSIGNALED(results[1]),
            os.WIFEXITED(results[1]))
        )
    if os.WIFEXITED(results[1]):
        print("exit code: %r" % (os.WEXITSTATUS(results[1])))

if __name__ == '__main__':
    try:
        pid = os.fork()
        if pid:
            print("in parent. child pid: %r" % (pid))
            while True:
                waitpid_result = os.waitpid(pid, os.WNOHANG)
                show_waitpid_results(waitpid_result)
                if waitpid_result == (0,0) or waitpid_result == (0,-512):
                    time.sleep(.1)
                    pass
                else:
                    break
            print("parent exiting")
        else:
            # child
            time.sleep(.5)
            print("child exiting with exit code 10");
            sys.exit(10)
    except Exception:
        e = sys.exc_info()[1]
        print("error: %s"%(e))
        sys.exit(20)

不正确？ FreeBSD上的行为（Python 2.7.12）：

in parent. child pid: 3196
results: (0, 0)
core: False continued: False stopped: False signaled: False exited True
exit code: 0
results: (0, 0)
core: False continued: False stopped: False signaled: False exited True
exit code: 0
results: (0, 0)
core: False continued: False stopped: False signaled: False exited True
exit code: 0
results: (0, 0)
core: False continued: False stopped: False signaled: False exited True
exit code: 0
results: (0, 0)
core: False continued: False stopped: False signaled: False exited True
exit code: 0
child exiting with exit code 10
results: (0, 0)
core: False continued: False stopped: False signaled: False exited True
exit code: 0
results: (3196, 2560)
core: False continued: False stopped: False signaled: False exited True
exit code: 10
parent exiting

我在FreeBSD下也见过-2048 vs. -512。

当使用in parent. child pid: 5054 results: (0, -512) core: False continued: False stopped: False signaled: False exited True exit code: -2 results: (0, -512) core: False continued: False stopped: False signaled: False exited True exit code: -2 results: (0, -512) core: False continued: False stopped: False signaled: False exited True exit code: -2 results: (0, -512) core: False continued: False stopped: False signaled: False exited True exit code: -2 results: (0, -512) core: False continued: False stopped: False signaled: False exited True exit code: -2 child exiting with exit code 10 results: (5054, 2560) core: False continued: False stopped: False signaled: False exited True exit code: 10 parent exiting时，可能在FreeBSD上没有正确初始化状态值（返回元组中的第二个元素）？我可以不依赖waitpid返回os.WNOHANG吗？

在FreeBSD下使用os.WNOHANG时，os.waitpid的状态值是否不可靠？

0 个答案: