Re: [Jython-users] File lock issue

[Philip J. <pj...@un...>]

On Sep 28, 2009, at 1:29 PM, Tobias Ivarsson wrote:

> Ok, I've discussed this with my colleague, and the only solution is  
> to not use memory mapped IO on Windows. Performance of regular IO  
> buffers on Windows is (according to his benchmarks) even slightly  
> better than the memory mapped ones on Windows (oddly enough).
>
> The next step on this issue is to look at the IO code in Jython  
> (this is not a part of Jython I've been involved with that much) to  
> verify that this actually is the problem, and then modify it so that  
> Jython doesn't use memory mapped IO on Windows.

We don't do use mmapped IO. I think this is just ElementTree.parse  
assuming CPython ref counting and not closing its file handles,  
combined with the fact that Windows disallows removal of a file when  
it's in use.

Gareth, could you please log a ticket for this on the bug tracker?

>
> I don't have the time to look deeper into this at the moment, so if  
> someone else on the dev team has some time over to take a look at  
> this, that would be great.
>
> Cheers,
> Tobias
>
> On Mon, Sep 28, 2009 at 8:16 PM, Tobias Ivarsson <th...@gm...>  
> wrote:
> I know there is an issue with file locks being retained after files  
> are closed on Windows:
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4715154
>
> And I think the features that trigger this bug are used in Jython.  
> The symptoms described here are exactly the ones I've seen with this  
> issue before.
>
> I know a guy with excellent knowledge in this area, I'll get back  
> when I've consulted him on how this can be worked around on the  
> insides of Jython. Until then your best bet is to use a better  
> operating system.
>
> cheers,
> Tobias
>
> On Mon, Sep 28, 2009 at 4:53 PM, DOUTCH GARETH-GDO003 <Gar...@mo... 
> > wrote:
> Hi there,
>
> I have a problem with an xml file locking after read and/or write.
>
> I have a short sample code with unit test attached. Below are the  
> outputs from Jython and CPython (v 2.5.4). Is this a bug?
> Can anybody offer an alternative workaround?
>
> I am using Jython 2.5.1 on Windows XP and java version "1.6.0_16".
>
> Cheers,
>
> Gareth
>
>
> >jython lock.py
> E
> ======================================================================
> ERROR: runTest (__main__.TestDelete)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>   File "W:\testTeam\SIT\JySit\sit\scripts\lock.py", line 73, in  
> tearDown
>     os.remove(self.fileName)
>   File "C:\jython2.5.1\Lib\os.py", line 342, in remove
>     raise OSError(0, "couldn't delete file", path)
> OSError: [Errno 0] couldn't delete file: 'C:\\testdir\\test.xml'
>
> ----------------------------------------------------------------------
> Ran 1 test in 0.454s
>
> FAILED (errors=1)
>
>
> >python lock.py
> .
> ----------------------------------------------------------------------
> Ran 1 test in 0.015s
>
> OK
>

--
Philip Jenvey