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From: Andy Seaborne Sent: sábado, 4 de febrero de 2017 16:56 To: [email protected] Subject: Re: ResultSetFactory.copyResults performance doubt On 03/02/17 21:41, George News wrote: > Hi all, > > On my environment I have created a class in order to encapsulate access > to `Dataset` and `Model`s stored. I didn't realize that the > `QueryExecution` instance was not collected by the GC Just because It should GC'ed. This depends on the storage but all the memory ones and TDB that come with Jena itself don't rely on ".close()". It is as much a case of recognizing that QueryExecution is use-once. > and it seems that > could lead to memory leak. In this sense I found that > `ResultSetFactory.copyResults()` detach the `ResultSet` from the > QueryExecution. ResultSetFactory.copyResults() is materializing the results and creating a List<> to keep them in so it isn't a huge copy. If the app is going to iterate over all the results, this is more a case of moving where work is done, not increasing or decreasing the work. > My concern now now is about performance: ¿Is it really consuming to > perform a copy of thousands of data? Would it be better to create > another class acting as a wrapper for the Jena `QueryExecution` and just > only read the `ResultSet` once. > > This is the kind of thing I'm referring to. > > ```java > // query is a Query > // ts is the class encapsulating the management of the triple store > SparqlExecutor exec = new SparqlExecutor(query, ts); > ResultSet res = exec.execute(); > // Do what ever with the resultset > exec.close() > > ``` > > Within the `execute` function I manage the transaction, get the > corresponding named graphs, etc. JENA-1215 : ResultSetCloseable -- this will be in Jena 3.2.0. This may help if you want to pass the ResultSet around - it keeps the QueryExecution around to close it. Andy That’s great. This is actually my class 😊 I’m just waiting for the voting to finish jejeje > > Thanks a lot. > > Jorge > > P.S.: It is difficult to explain things without disclosing the code :( > sorry. >
