Java中具有并行化的链接过滤器

Question

I am trying to parse an input into an output by applying a sequence of transformations t0, t1, ..., tn . The execution will be a chain:

input -> t0 -> t1 -> ... -> tn -> output

Some of the transformations should be parallelized, to prevent becoming a bottleneck.

Is there any framework for creating such a process chain in Java? I know how I could do it manually (eg Queuing jobs in a processing chain in Java ) but I am specifically looking for a framework, since

• The complexity of a longer (partially) multithreaded chain with caches, waits, ... can quickly become complex
• I have several such chains and want to avoid reinventing what might be covered in a standard library

Answer 1

I believe the fork/join framework (in jdk 7) is what you are looking for. it enables specifying task dependencies and splitting jobs into more parallel chunks depending on available resources.

Answer 2

There exist many different execution models to express such a transformation chain. Transformations can be threads with loops reading from input queues, or objects with a method to handle each incoming message (threads and loops hidden under the hood). Transformation may have single input or several inputs. It may know its successors and send them results directly, or just return a value from method, and a separately described topology takes care of further message routing. Availability of space to hold results may or may not be taken into account when a transformation act is started, and so on. A transformation act may be very short, so overhead for message passing is significant, and message passing should be carefully optimized (see Disruptor), or ordinary linked queue generating wrapper objects for each message would suffice.

It is said, it is hard to give an advice without knowing your requirements. You should explore which models and implementations exist and find out most appropriate for your case. Without knowing details, advices like "I believe framework XYZ is what you are looking for" only describe advisor as a person who hardly knows other frameworks besides XYZ. Nevertheless, I dare to recommend you to look at Dataflow Framework for Java , whose model is reach enough, though has its limitations (eg execution nodes may not block).

Answer 3

As Alexei said about advice, let the buyer beware. I just happen to maintain a Fork/Join framework on SourceForge that supports filters. Since the code is free and open-source, you can use it as is or do what you want. TymeacDSE