Skip functionality is not working properly in MongoItemReader scenario [BATCH-2503]

nishant ranjan opened BATCH-2503 and commented

Skip exception class functionality is not working properly when MongoItemreader is being used.
Example:
<skippable-exception-classes>
<include class="org.springframework.core.convert.ConversionFailedException" />
</skippable-exception-classes>

Suppose 20 rows are fetched from MongoDB and at row number 15 configurable exception ".ConversionFailedException" is thrown from a custom class derived from Converter, (MessageContextReadConverter implements Converter<DBObject, MessageContext>)
. MessageContextReadConverter is set during mongoTemplate creation,.

Now, exception thrown at row number 15 is received in custom readlistener (public void onReadError(Exception ex)).

Issues:

1. Spring batch is stuck at row number 15. It continuously calls MessageContextReadConverter and onReadError for same row number 15.
2. skiplistener is never invoked.

Analysis:
MongoItemreader works on paging mechanism therefore skip functionality is not working.

Solution:

1. Spring batch should provide MongoItem reader which is a cross implementation of both page and cursor techniques. Otherwise, reading each row from Mongo is huge task if data is large.

Kindly correct me if above analysis is in-correct.

I am implementing cursor based reader but again its not a solution as combination of cursor + paging is required.

Affects: 3.0.7

Start by examining the MongoItemReader paging behavior in the reported 3.0.7 scenario and the configured ConversionFailedException path. Reproduce the failure at row 15, observing repeated MessageContextReadConverter calls and onReadError without skiplistener invocation. Done means the Mongo reader applies configured skip handling without looping, with coverage for this case.