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From Sean Owen <sro...@gmail.com>
Subject Re: deadlock in FastByIDMap.find() ?
Date Sun, 06 Dec 2009 00:12:48 GMT
If he's using the normal class APIs, then shouldn't matter what the
heck is being done to the class. I can't spot a problem that would
fill up the hash table.

I don't think he's messing with the implementation or data structures directly?

But yes I am still quite puzzled, I haven't seen this, can't reproduce
it even with some tests that guess at pathological patterns, and can't
see anything wrong with the logic. I'm stumped on this one.

On Sat, Dec 5, 2009 at 7:54 PM, Ted Dunning <ted.dunning@gmail.com> wrote:
> Is it possible that weiwei is filling the fastMap explicitly?
>
> On Sat, Dec 5, 2009 at 1:31 AM, Sean Owen <srowen@gmail.com> wrote:
>
>> That all sounds fine, should be no problem with this usage pattern. I
>> don't think the issue is where you think it is -- The problem seemed
>> to be with the FastMap used to cache recommendations. Is there
>> anything interesting about how this is used? I just added a couple
>> unit tests for the cache to try to reproduce it but didn't see
>> anything.
>>
>> You can remove CachingRecommender to see what happens but that would
>> be a shame since it's just avoiding the problem. If there's an issue
>> I'm keen to track it down.
>>
>> I can't figure out what the issue is. Maybe I can add some asserts to
>> the code that could trigger some signs of a problem.
>>
>> 2009/12/5 施伟伟 <shiweiwei97@gmail.com>:
>> > Thanks for reply.
>> > It does not happen all the time. I saw this twice and could not easily
>> > reproduce it.
>> > Next time I will try testing it with jpda enabled.
>> >
>> > I am not sure if I am doing something wrong in the data model.
>> > First I fill the FastMap with data read from external data source.
>> > Then I iterate all entries in FastMap and find a set of items that I
>> don't
>> > need.
>> > Finally I iterate the entries again to remove those items from FastMap.
>> If
>> > the item set of any userID becomes empty, the userID will be removed from
>> > FastMap too.
>> >
>> > Maybe I should do these outside mahout using ordinary Map?
>> >
>> > Thanks,
>> > Weiwei
>> >
>>
>
>
>
> --
> Ted Dunning, CTO
> DeepDyve
>

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