I wonder what would the deployment-initialization do? btw, the UDF does have a deinitialize() method which is expected to be invoked when the UDF is deinitialized, but that's is ignored for now as the IScalarEvaluator in general doesn't not deinitialize. To make that work, we would need a bigger change in Hyracks to make it aware that step. This could one improvement as well...
Best, Xikui On Sun, Nov 17, 2019 at 11:30 AM Till Westmann <[email protected]> wrote: > It seems that it's be nice if we had a step (similar to the > initialization step) in the deployment lifecycle as well. > And I guess that we'd need to corresponding clean-up step for > un-deployment as well. > > Does that make sense? If so, should we file an improvement for this? > > Cheers, > Till > > On 17 Nov 2019, at 9:29, Xikui Wang wrote: > > > The UDF interface has an initialize method which is invoked per every > > lifecycle. Putting the model loading code in there can probably solve > > your > > problem. The initialization is done per query (Hyrack job). For > > example, if > > you do > > > > SELECT mylib#myudf(t) FROM Tweets t; > > > > in which there are 100 tweets in the Tweets dataset. The > > initialization > > method will be called once and the evaluate method will be invoked 100 > > times. In the context of feeds attached with UDFs, the > > initialization happens only once when feed starts. > > > > Best, > > Xikui > > > > On Sun, Nov 17, 2019 at 6:44 AM Torsten Bergh Moss < > > [email protected]> wrote: > > > >> Dear developers, > >> > >> > >> I am trying to build a machine learning-based UDF for classification. > >> This > >> involves loading in a model that has been trained offline, which in > >> practice basically is deserialization of a big object. This process > >> of > >> deserialization takes a significant amount of time, but it only > >> "needs" to > >> happen once, and after that the model can do the classification > >> rather > >> rapidly. > >> > >> > >> Therefore, in order to avoid having to load the model every time the > >> UDF > >> is called, I am wondering where in the UDF lifecycle I can do the > >> loading > >> in order to achieve a "load model once, classify > >> infinitely"-scenario, and > >> how to implement it. I am assuming it should be done somewhere inside > >> the > >> factory-function-relationship, but I am not sure where/how and can't > >> seem > >> to find a lot of documentation on it. > >> > >> > >> All help is appreciated, thanks! > >> > >> > >> Best wishes, > >> > >> Torsten > >> >
