java vs scala - reading in file on a separate thread

Question

I would like to know what the best in terms of industry practice way is to read in a file using multithreaded approach. In Java I would do something of the following sort:

class Reader {  Result readFile(File file, Listener callback) }
class Listener { void process(Result r) }

Reader would spawn another thread to generate a result and then call back the Listener from withing the working thread. Would this be a good approach? How would this translate into Scala, which probably has other, better mechanisms to achieve this?

It's not clear (to me at least) whether you're trying to read one file or many. If it's many files, then Kim Stebel's answer is better. If it's a single file that needs results processed on different threads, then the other answer seems better. — Ian McLaird
– Ian McLaird, Commented Oct 8, 2012 at 21:07
What do you mean "better"? Shorter code? Probably yes. More performant? Probably not, as Scala generates a lot of code behind the scenes. — Alexei Kaigorodov
– Alexei Kaigorodov, Commented Oct 9, 2012 at 1:19
if he wants every line in the file processed concurrently, he can still do that with parallel collections. — Kim Stebel
– Kim Stebel, Commented Oct 9, 2012 at 4:24

Kim Stebel · Accepted Answer · 2012-10-08 19:52:36Z

7

One approach in Scala would be to use parallel collections. Say you have a sequence of files:

files:Seq[File] = ...

You can turn it into a parallel collection using files.par and then use map to do the processing. Map will internally use a thread pool to process parts of the sequence concurrently. What kind of thread pool is used can be configured.

files.par.map(readFile).foreach(process)

edited Oct 8, 2012 at 19:52

answered Oct 8, 2012 at 19:47

Kim Stebel

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Jordan Denison · Accepted Answer · 2012-10-08 19:46:34Z

1

This seems like it would be a good use case for Akka if you wanted an alternate approach.

answered Oct 8, 2012 at 19:46

Jordan Denison

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1 Comment

Alexei Kaigorodov Over a year ago

Akka is just an actor framework and afaik can be used from Java. There are a lot of other actor framworks for java also.

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