MultiResourceItemWriter and itemCountLimitPerResource

[Christian Gossart]

Hi all,

I'm using MultiResourceItemWriter to split the output of a chunk oriented tasklet with commit-interval = itemCountLimitPerResource.

This was producing the expecting result (several output files with a maximum of itemCountLimitPerResource lines per file), until I set the item read number as a multiple of itemCountLimitPerResource with the following scenario:
- commit-interval = itemCountLimitPerResource = 5,
- read a 10 lines file,
- process
- write using MultiResourceItemWriter and a FlatFileItemWriter as a delegate.

This produces 3 output files (and not 2 as I expected): 2 with 5 lines each, and an empty 3rd one. I dug into MultiResourceItemWriter source code, and the

setResourceToDelegate()

method, which create the file on the filesystem via

file.createNewFile()

is called on MultiResourceItemWriter.open() and in MultiResourceItemWriter.write() when if

(currentResourceItemCount >= itemCountLimitPerResource)

Hence, just after writing the last item in the 2nd file, the value of currentResourceItemCount is 5, and the test passes: a 3rd file is created on the filesystem, but nothing will be written into it, because the last input item has been read, processed and written.
I wonder if this is a bug, or if there is a good reason for this I didn't see.

Also, I wanted to subclass MultiResourceItemWriter and only override the needed methods, but nearly everything is private (protected access of fields and methods should be the way to go for a framework like Spring Batch). I think

file.createNewFile()

should only be called if the file is not already opened on MultiResourceItemWriter.write(), and then passed to the delegate writer.

Did anyone encountered this kind of behavior?

Spring Batch version: 2.1.1 Release.

Christian.

[Dave Syer]

I think someone else noticed this but I don't remember a JIRA issue, so please feel free to open one (it seems trivial so expect a fix in 2.1.x).

[Christian Gossart]

I created a JIRA issue https://jira.springframework.org/browse/BATCH-1618 and proposed a patch.