RotatingFileHandler + subprocess module problems

Stephen Hansen shansen at advpubtech.com
Tue Jan 16 06:48:33 CET 2007


That was perfect-- it now all behaves as it should. Thanks!

On 1/11/07, Gabriel Genellina <gagsl-py at yahoo.com.ar> wrote:
>
> At Thursday 11/1/2007 15:59, Stephen Hansen wrote:
>
> >If I run app1, and then app2, it all works fine. Specifically, the
> >apps are logging correctly and I can see with Process Explorer that
> >each has a handle to the appropriate files.
> >
> >However, I have a setting to make App2 run App1 in the background
> >for convienance. This is using the subprocess module. When this
> >setting is on, App2 will die horribly the first time that the
> >doRollover comes along: specifically it gets a permission denied
> >error when it tries to rename App2.log to App2.log.1
> >
> >After doing some debugging, it appears that App1 (if started by App2
> >using the subprocess module) has a handle to App2.log /somehow/. It
> >never starts it, or touches it (verified through debug messages),
> >but seems to inherit it.
>
> That's subprocess fault. You menctioned Process Explorer, it appears
> you're using Windows.
> Using subprocess, the child process always inherits all file handles
> from its parent. This may or may not be desirable, and in your case,
> it's not. App1 inherits the open file handle to App2.log.
> Inside subprocess.py, near line 789, there is a call to
> CreateProcess; its 5th parameter is called bInheritHandles and it's
> set to 1. The comment "must inherit handles to pass std handles" is
> wrong AFAIK, and setting STARTF_USESTDHANDLES in startupinfo   should
> be enough. (It may be that some lines above, STARTF_USESTDHANDLES is
> not correctly set).
> I'll try to investigate a bit more and file a bug report or a patch.
> In the meantime, you could replace that 1 in CreateProcess by a 0.
> Specially if you don't use PIPE or redirects, your problem should go away.
>
>
> --
> Gabriel Genellina
> Softlab SRL
>
>
>
>
>
>
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