5.1 Chunk-Oriented Processing does not represent the actual implementation [BATCH-2423]

[spring-projects-issues]

Iwasa Kazmi opened BATCH-2423 and commented

In reference documentation, diagram and code of concept in the section "5.1 Chunk-Oriented Processing" http://docs.spring.io/spring-batch/trunk/reference/html/configureStep.html#chunkOrientedProcessing
seems to be different from the actual implementation of the ChunkOrientedTasklet.

According to the description, ItemProcessor will be called immediately after the ItemReader was called once.

In actual implementation of ChunkOrientedTasklet, ItemReader will be called repeatedly for collecting item, then ItemProcessor will be called repeatedly for each collected items.

Current description may lead to the wrong step design and may lead to the performance issue.

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Affects: 4.0.1, 4.1.0.RC1

Reference URL: https://stackoverflow.com/questions/26655281/spring-batch-documentation-about-chunk-oriented-step-versus-reality

Issue Links:

• BATCH-2534 Commit interval
  ("is duplicated by")

1 votes, 3 watchers

[spring-projects-issues]

Mahmoud Ben Hassine commented

According to this answer on SO by Michael, I do also confirm that the documentation is misleading and is different from the current implementation. In the most basic form of ChunkOrientedTasklet, there are two calls:

Chunk<I> inputs = chunkProvider.provide(contribution);
chunkProcessor.process(contribution, inputs);

The ChunkProvider uses the ItemReader to read commit-interval items (or less if the item reader returns null). And the ChunkProcessor uses ItemProcessor and ItemWriter to process and write items:

Chunk<O> outputs = transform(contribution, inputs);
write(contribution, inputs); // details of adjustments of output omitted here

[fmbenhassine]

This is a duplicate of #1629.