[developers] [incr() tsdb]/LKB memory allocation error
Ann Copestake
aac10 at cl.cam.ac.uk
Sat Apr 9 21:42:43 CEST 2016
OK, I was in fact going to ask whether there was a way of combining the
rules so you didn't have so many of them. It's not the type of thing
the system is designed to cope with, to be honest.
All best,
Ann
On 09/04/2016 17:45, Olga Zamaraeva wrote:
> Dear Ann,
>
> You know, no, I did not find a work around yet, but I decided to leave
> it alone for a little while. It only happens with two of my grammars,
> and they are just unrealistically large, there really should not be so
> many lexical rule instances with the same orthography. Not dozens of
> them, I don't think. So I decided for now that it is not very
> important that I cannot use those two grammars for parsing. I sort of
> evaluated them on a smaller test set, and I think this will do for now.
>
> Thank you!
> Olga
>
> On Sat, Apr 9, 2016 at 7:32 AM Ann Copestake <aac10 at cl.cam.ac.uk
> <mailto:aac10 at cl.cam.ac.uk>> wrote:
>
> Dear Olga,
>
> Sorry for not replying - did you manage to find a work around?
>
> Ann
>
>
>
> On 24/03/2016 21:55, Olga Zamaraeva wrote:
>> Looking at the token chart, I see that I in fact have many
>> lexical rules for the same orthography, and that results in too
>> many parses (a snippet of the output is attached). For example,
>> for this "a-tis-e" input that I am trying, there are dozens
>> lexical rules for a- and dozens for -a, and so the combinations
>> are too many. The reason for this is because the rules were
>> inferred automatically by a clustering algorithm, and I asked for
>> many clusters (there is a reason for asking for many clusters
>> also: I am trying to compare these results with another algorithm
>> which happened to infer many position classes, so I want my
>> clustering to come up with the same number and then to compare
>> two grammars).
>>
>> Is there a way to have the LKB stop after it found a parse, and
>> not try other possibilities? I tried doing that in itsdb (by
>> turning off exhaustive search and limiting the maximum number of
>> analyses), but it still cannot handle this large grammar for some
>> reason...
>>
>> Thank you!
>> Olga
>>
>> On Thu, Mar 17, 2016 at 1:34 AM Ann Copestake <aac10 at cl.cam.ac.uk
>> <mailto:aac10 at cl.cam.ac.uk>> wrote:
>>
>> So the process is running out of memory before hitting the
>> limit on the number of chart edges, which stops processing a
>> little more gracefully. The LKB batch parse process catches
>> some errors in a way that allows the rest of the batch to
>> continue. It may be that all that's happening is that the
>> chart edge limit was set too high relative to the available
>> memory, although it is possible that memory is being used in
>> a way that isn't reflected by the edge limit, which is why I
>> suggested also looking at the token chart. You could
>> increase the amount of memory available to the process and
>> see whether you can get your test set through, but unless
>> that's the final test set and you don't intend to work on any
>> more complex examples than the ones you have, that's only
>> going to be a temporary measure.
>>
>> I don't think it will matter whether you look at examples
>> that can eventually be parsed, something that fails after a
>> huge number of edges or something that causes the memory
>> crash - your task is to find out whether there is something
>> you can do to cut down the number of rule applications. The
>> good news is that you won't need to find many cases of
>> over-application to make a dramatic improvement. I think you
>> will see the issues with the grammar when you look at a
>> chart, even with a small edge limit.
>>
>>
>> Ann
>>
>>
>> On 17/03/2016 01:55, Olga Zamaraeva wrote:
>>> Thank you Ann!
>>>
>>> I suppose I should try to pin down an input that can be
>>> successfully parsed, but does produce a huge chart. Of
>>> course my most pressing problem is not that some inputs are
>>> parsed with huge charts but that some inputs can never be
>>> parsed and break the system. But perhaps this is caused by
>>> the same problem (or feature) in the grammar.
>>>
>>> The LKB does give an error message, the same memory
>>> allocation error that comes through itsdb when that breaks
>>> (attached in the original email).
>>>
>>> Olga
>>> On Tue, Mar 15, 2016 at 2:19 PM Ann Copestake
>>> <aac10 at cl.cam.ac.uk <mailto:aac10 at cl.cam.ac.uk>> wrote:
>>>
>>> I would say that you should attempt to debug in the
>>> LKB. I don't know
>>> exactly why [incr() tsdb] crashes while the LKB batch
>>> fails more
>>> gracefully (does the LKB give an error message?) but you
>>> should try and
>>> understand what's going on to give you such a huge
>>> chart. That's not to
>>> say that it wouldn't be a good idea to know what the
>>> [incr() tsdb] issue
>>> is, but it probably won't help you much ...
>>>
>>> If you're using the LKB's morphophonology, you might
>>> want to look at the
>>> token chart as well as the parse chart. This is more
>>> recent than the
>>> book, so isn't documented, but if you have an expanded
>>> menu, I think it
>>> shows up under Debug. You want the `print token chart'
>>> item, which will
>>> output to the emacs window. Similarly, if you're trying
>>> to debug what's
>>> going on and have an enormous parse chart, don't try and
>>> look at the
>>> chart in a window, but use the `print chart' option.
>>> You would want to
>>> reduce the maximum number of items to something a lot
>>> smaller than 20k
>>> before you try that, though.
>>>
>>> We should have a FAQ that says `ignore all the GC
>>> messages'. It's
>>> really just a symptom of the underlying system running
>>> out of space -
>>> nothing to do with the LKB or [incr() tsdb] as such. So
>>> there's not a
>>> lot of enlightenment to be gained by understanding terms
>>> like tenuring ...
>>>
>>> Best,
>>>
>>> Ann
>>>
>>> On 15/03/2016 19:55, Olga Zamaraeva wrote:
>>> > Dear developers!
>>> >
>>> > I am trying to use the LKB and [incr() tsdb] to parse
>>> a list of verbs
>>> > by a grammar of Chintang [ctn]. The language is
>>> polysynthetic, plus
>>> > the grammar was created automatically using k-means
>>> clustering for the
>>> > morphology section, so some of the position classes
>>> have lots and lots
>>> > of inputs and lots and lots of lexical rule types and
>>> instances.
>>> >
>>> > I am running into a problem when [incr() tsdb] crashes
>>> because of a
>>> > memory allocation error. If I don't use itsdb and just
>>> go with LKB
>>> > batch parsing, it is more robust as it can catch the
>>> error and
>>> > continue parsing, having reported a failure on the
>>> problematic item,
>>> > but the problem is still there and the parses still fail.
>>> >
>>> > I am a fairly inexperienced user of both systems, so
>>> right now I am
>>> > trying to understand what is the best way for me to:
>>> >
>>> > 1) debug the grammar with respect to the problem,
>>> i.e. what is it
>>> > about the grammar exactly that causes the issues;
>>> > 2) do something with itsdb so that perhaps this does
>>> not happen? Limit
>>> > it somehow so that it doesn't try as much?
>>> >
>>> > Currently I am mostly just trying to filter out the
>>> problematic
>>> > items... I also tried limiting the chart size to 30K,
>>> and that seems
>>> > to have helped a little, but the crashes still happen
>>> on some items.
>>> > If I limit the chart size to 20K, then it seems like
>>> maybe I can go
>>> > through the test suite, but then my coverage suffers
>>> when I think it
>>> > shouldn't: I think there are items which I can parse
>>> with 30K limit
>>> > but not 20K... Is this the route I should be going in
>>> any case? Just
>>> > optimizing for the chart size?.. Maybe 25K is my
>>> number :). The chart
>>> > is the parse chart, is that correct? I need to
>>> understand what exactly
>>> > makes the chart so huge in my case; how should I
>>> approach debugging
>>> > that?..
>>> >
>>> > One specific question: what does "tenuring" mean with
>>> respect to
>>> > garbage collection? Google doesn't know (nor does the
>>> manual, I think).
>>> >
>>> > Does anyone have any comment on any of these issues?
>>> The (very
>>> > helpful) chapter on errors and debugging in Copestake
>>> (2002) book
>>> > mostly talks about other types of issues such as type
>>> loading problems
>>> > etc.. I also looked at what I found in ItsdbTop
>>> > (http://moin.delph-in.net/ItsdbTop), and it does
>>> mention that on
>>> > 32-bit systems memory problems are possible, but I
>>> think that note has
>>> > to do with treebanking, and it doesn't really tell me
>>> much about what
>>> > I should try in my case... I also looked thorough the
>>> itsdb manual
>>> >
>>> (http://www.delph-in.net/itsdb/publications/manual.pdf)
>>> -- but it
>>> > looks like some of the sections, specifically about
>>> debugging and
>>> > options and parameters, are empty?
>>> >
>>> > Anyway, I would greatly appreciate any advice! I
>>> attach a picture of a
>>> > running testsuite processing, to give an idea about
>>> the memory usage
>>> > and the chart size, and of the error. It is possible
>>> that the grammar
>>> > that I have is just not a usage scenario as far as
>>> itsdb is concerned,
>>> > but I don't yet have a clear understanding of whether
>>> that's the case.
>>> >
>>> > Thanks!
>>> > Olga
>>>
>>
>
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