从python调用BCP会抛出超时异常，然后立即完成

Question

我正在运行一个调用子流程的python脚本。它超时了，然后我立即看到子进程（在本例中是BCP调用）完成。事实上，我可以在数据库中看到它是完整的。此外，我可以直接在命令行上运行BCP命令，它运行得很好。

以下是我的python脚本向命令提示符吐出的内容：

C:FaceIAPSStudyDataFiles> py .RUN_DATA.py
Synchronizing 80 subjects
Subject 11
Starting copy...
Traceback (most recent call last):
  File ".RUN_DATA.py", line 261, in <module>
    bulk_import(upload_file, 'Facet_Data')
  File ".RUN_DATA.py", line 171, in bulk_import
    subprocess.check_call("bcp BehaviorResearch.." + table_to_upload_to + " in " +     filename_to_be_uploaded + " -T -c -S
PBB-C202B-2BEHAVIORRESEARCH -e bulk_copy_errors.log", shell=True, timeout=5)
  File "C:Python34libsubprocess.py", line 554, in check_call
    retcode = call(*popenargs, **kwargs)
  File "C:Python34libsubprocess.py", line 537, in call
    return p.wait(timeout=timeout)
  File "C:Python34libsubprocess.py", line 1157, in wait
    raise TimeoutExpired(self.args, timeout)
subprocess.TimeoutExpired: Command 'bcp BehaviorResearch..Facet_Data in _temp_ -T -c -S     PBB-C202B-2BEHAVIORRESEARCH -e
bulk_copy_errors.log' timed out after 5 seconds
1000 rows sent to SQL Server. Total sent: 1000
1000 rows sent to SQL Server. Total sent: 2000
PS C:FaceIAPSStudyDataFiles> 1000 rows sent to SQL Server. Total sent: 3000
1000 rows sent to SQL Server. Total sent: 4000
1000 rows sent to SQL Server. Total sent: 5000
1000 rows sent to SQL Server. Total sent: 6000
1000 rows sent to SQL Server. Total sent: 7000
1000 rows sent to SQL Server. Total sent: 8000
1000 rows sent to SQL Server. Total sent: 9000
1000 rows sent to SQL Server. Total sent: 10000
1000 rows sent to SQL Server. Total sent: 11000
1000 rows sent to SQL Server. Total sent: 12000
1000 rows sent to SQL Server. Total sent: 13000
1000 rows sent to SQL Server. Total sent: 14000
1000 rows sent to SQL Server. Total sent: 15000
1000 rows sent to SQL Server. Total sent: 16000
16102 rows copied.
Network packet size (bytes): 4096
Clock Time (ms.) Total     : 5164   Average : (3118.13 rows per sec.)

正如您所看到的，命令提示符已与BCP调用的输出分开
发生了什么事，我该如何解决？

编辑：我是如何修复的

将子流程调用更改为：

arguments = ["bcp", "BehaviorResearch.." + table_to_upload_to, "in", filename_to_be_uploaded, "-T", "-c", "-S PBB-C202B-2BEHAVIORRESEARCH", "-e bulk_copy_errors.log"]
subprocess.call(arguments, timeout=30)

作为外行的参考，"in"是它自己的论点。

Answer 1

subprocess.check_call()的文档说：

timeout参数被传递给Popen.wait（）。如果timeout到期时，子进程将被终止，然后再次等待。TimeoutExpired异常将在子进程之后重新引发已终止。

subprocess源代码确认：

def call(*popenargs, timeout=None, **kwargs):
    with Popen(*popenargs, **kwargs) as p:
        try:
            return p.wait(timeout=timeout)
        except:
            p.kill() # kill on any exception including TimeoutExpired
            p.wait()
            raise

也就是说，您看到的是预期的行为：如果发生超时，那么运行bcp进程的shell（%COMSPEC%或cmd.exe）应该立即终止，这反过来可能会终止bcp进程本身。

在子进程已经退出或（我不确定）之后，您可以在控制台中看到缓冲输出被刷新。在父进程cmd.exe已经完成时，您可以看到活动孙进程bcp的输出（显示新提示）。

删除shell=True以避免创建不必要的中间cmd.exe进程，从而直接在bcp进程而不是shell进程上调用.kill()。