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From Aleksei Udatšnõi <>
Subject Re: Multi-user PlusAnonymousUserDataModel
Date Thu, 02 Feb 2012 10:51:03 GMT
Hi Sean,

The goal is to produce anonymous "cold start" user-based
recommendations in an environment of 100-200 concurrent users.

It may work in a synchronized way as is with only one fixed
TEMP_USER_ID. However while one anonymous user insert its temp data
into the model, other threads have to wait until the TEMP_USER_ID is

With high volume of concurrent users, it may become a serious
bottleneck. So I would like to improve the throughout.

If you find it is not a useful feature for core, I can implement it in
my custom recommender.


On Thu, Feb 2, 2012 at 11:21 AM, Sean Owen <> wrote:
> Why does this make it useful in a multi-user environment? you can already
> use it just fine, with synchronization.
> I am wary of making this hacky wrapper more complex.
> 2012/2/2 Aleksei Udatšnõi <>
>> Hello,
>> I would like to make a change to PlusAnonymousUserDataModel. Currently
>> the ID of the anonymous user is fixed to Long.MIN_VALUE. Only one set
>> of temp data can be inserted into the model and used at one time.
>> I propose the change to enable multiple users to insert into this
>> model concurrently in a thread-safe manner.
>> The idea is to define a pool of available anonymous user IDs. Every
>> time a new anonymous user makes a request, the next available
>> TEMP_USER_ID is pulled from the queue. After recommendations are
>> retrieved, the TEMP_USER_ID can be returned to the pool.
>> As the result this model will become usable in a production multi-user
>> environment.
>> Waiting for your feedback,
>> Aleksei

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