Re: subprocess & redirect

On Mar 22, 2006, at 6:45 PM, Philip Semanchuk wrote:
> On Mar 21, 2006, at 4:45 PM, Jonathan Ellis wrote:
>
>> Strange.  My first guess would be that the child process is somehow
>> interacting with stdout (which Spyce redirects to an internal file
>> handle) which screws things up here.  But even when I specify
>> subprocess.PIPE for the subprocess stdin/out/err I get the same 
>> results.
>>  So I don't know.  Let me know if you figure it out. :)

Jonathan,
You were correct, although it wasn't stdout that was the problem (even 
though that makes the most sense). If I supply the parameter 
"close_fds=True" to subprocess.Popen(), the problem goes away. The 
documentation says, "If close_fds is true, all file descriptors except 
0, 1 and 2 will be closed before the child process is executed." So it 
sounds like the child process was holding open some file and Spyce's 
processing couldn't complete until the child exited and the file was 
closed.

Oddly enough, redirecting the stdin/stdout/stderr of the child process 
doesn't seem to make a difference.

Anyway, just for clarity here's the working code:

[[\
     import subprocess
     import time

     TheLongRunningProcess = "/usr/local/MyStuff/src/foo.py"

     subprocess.Popen(["python", TheLongRunningProcess], close_fds=True)

     response.write("<p>Spawn complete at %s</p>\n" % 
time.strftime("%M:%S", time.gmtime()))
]]


Bye all
Philip



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