[yt-users] reloading pf does not reflect changes in the hierarchy

[j s oishi]

thanks, btw!

On Wed, Mar 20, 2013 at 1:04 PM, j s oishi <jsoishi at gmail.com> wrote:
> Sounds like the answer is "restart the kernel."
>
> On Wed, Mar 20, 2013 at 1:02 PM, Matthew Turk <matthewturk at gmail.com> wrote:
>> On Wed, Mar 20, 2013 at 12:57 PM, j s oishi <jsoishi at gmail.com> wrote:
>>> Hi Matt,
>>>
>>> I can't be sure, but it doesn't seem like deleting it works. For now,
>>> I'll just restart the kernel. Not a huge deal.
>>
>> Well, if any other references to it exist, it will persist.
>>
>> At load time, the only information that yt has about a parameter file
>> is the filename passed in.  However, because we need to be able to
>> support identifying parameter files off of which pickled objects hang,
>> we need to use that information to identify which parameter file it
>> is.  So at load time, ever parameter file is pushed into a
>> WeakValueDictionary.  As long as a reference to the object exists,
>> that parameter file value in the key value dictionary will remain, and
>> will be used *instead of* a new instance of the parameter file.
>> Imagine a case where you have thousands of halo objects pickled, which
>> you then de-pickle, in a very large hierarchy.  If we weren't able to
>> do this, unpickling would create a new parameter file (and hierarchy)
>> instance for each one.  This keeps us from that eventuality.
>>
>> Note that IPython also retains references to items that have not been
>> assigned to variables, in variables whose names escape me at the
>> moment.  So you may have an object in one of those that references it.
>>
>> I would be open to alternate methods of identifying parameter files
>> and keeping singletons on a per-pf basis, but I couldn't (and still
>> can't) think of any...
>>
>>>
>>> j
>>>
>>> On Wed, Mar 20, 2013 at 10:51 AM, Matthew Turk <matthewturk at gmail.com> wrote:
>>>> Hi Jeff,
>>>>
>>>> On Wed, Mar 20, 2013 at 10:39 AM, j s oishi <jsoishi at gmail.com> wrote:
>>>>> Hi all,
>>>>>
>>>>> I'm not sure this is the proper use case, but I've noticed that if,
>>>>> using the iPython notebook you do
>>>>>
>>>>> pf = load("DD0000/DD0000")
>>>>>
>>>>> and then recreate DD0000 with a different hierarchy, when you rerun
>>>>> the load cell, the pf does not change its hierarchy. I don't know if
>>>>> this is an intentional behavior, or if I'm doing something wrong.
>>>>> Restarting the ipython notebook kernel fixes the problem. If the
>>>>> hierarchy stays the same but the data changes, this seems to work just
>>>>> fine. I'm trying to debug intial conditions, hence the repeated
>>>>> loading of a rapidly changing pf.
>>>>>
>>>>> Is this something we could fix? Or is it by design? If we're moving
>>>>> increasingly toward iPython notebooks, I would imagine reloading a pf
>>>>> as a fairly common use case.
>>>>
>>>> Delete it first, and I think it will work.
>>>>
>>>> -Matt
>>>>
>>>>>
>>>>> j
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