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https://issues.apache.org/jira/browse/HIVE-22221?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shubham Chaurasia updated HIVE-22221:
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Attachment: HIVE-22221.2.patch
> Llap external client - Need to reduce LlapBaseInputFormat#getSplits()
> footprint
> ---------------------------------------------------------------------------------
>
> Key: HIVE-22221
> URL: https://issues.apache.org/jira/browse/HIVE-22221
> Project: Hive
> Issue Type: Bug
> Components: llap, UDF
> Reporter: Shubham Chaurasia
> Assignee: Shubham Chaurasia
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-22221.1.patch, HIVE-22221.2.patch
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> While querying through llap external client, LlapBaseInputFormat#getSplits()
> invokes get_splits() (GenericUDTFGetSplits) udtf under the hoods.
> GenericUDTFGetSplits returns LlapInputSplit in which planBytes[] occupies
> around 90% of the split size.
> Depending on data size/partitions and plan, LlapInputSplit can grow upto 1mb
> with planBytes[] being common to all the splits and occupying more than 850
> kb. Also, it sometimes causes OOM on HS2 depending on HS2 heap size.
> This can be resolved by separating out common parts from actual splits and
> reassembling them at client side.
> We can also provide an option where client can say it does not want to
> reassemble them and can take the control of reassembling in it's hands.
> Splits can be broken like:
> 1) schema split
> 2) plan split
> 3) actual split 1
> 4) actual split 2....and so on.
> This greatly reduces the memory(in my case from 5GB(~5000 splits) to around
> 15MB) on server side and hence the data transfer. And this eliminates OOM on
> HS2 side.
> cc [~jdere] [~sankarh] [~thejas]
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