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https://issues.apache.org/jira/browse/IMPALA-12709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17817025#comment-17817025
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Venugopal Reddy K commented on IMPALA-12709:
--------------------------------------------
Have put the POC code to this WIP gerrit:
[https://gerrit.cloudera.org/#/c/21031/]
Have covered the positive cases. Yet to measure the performance. Do we have
performance testsuite for catalogd that can be used to measure ? Any baselined
performance report or specification about how to measure? Like what and how
much data to use for test etc. Any pointers/suggestions would be appreciated.
Thanks!
> Hierarchical metastore event processing
> ---------------------------------------
>
> Key: IMPALA-12709
> URL: https://issues.apache.org/jira/browse/IMPALA-12709
> Project: IMPALA
> Issue Type: Improvement
> Components: Catalog
> Reporter: Venugopal Reddy K
> Assignee: Venugopal Reddy K
> Priority: Major
> Attachments: Hierarchical metastore event processing.docx
>
>
> *Current Issue:*
> At present, metastore event processor is single threaded. Notification events
> are processed sequentially with a maximum limit of 1000 events fetched and
> processed in a single batch. Multiple locks are used to address the
> concurrency issues that may arise when catalog DDL operation processing and
> metastore event processing tries to access/update the catalog objects
> concurrently. Waiting for a lock or file metadata loading of a table can slow
> the event processing and can affect the processing of other events following
> it. Those events may not be dependent on the previous event. Altogether it
> takes a very long time to synchronize all the HMS events.
> *Proposal:*
> Existing metastore event processing can be turned into multi-level event
> processing. Idea is to segregate the events based on their dependency,
> maintain the order of events as they occur within the dependency and process
> them independently as much as possible:
> # All the events of a table are processed in the same order they have
> actually occurred.
> # Events of different tables are processed in parallel.
> # When a database is altered, all the events relating to the database(i.e.,
> for all its tables) occurring after the alter db event are processed only
> after the alter database event is processed ensuring the order.
> Have attached an initial proposal design document
> https://docs.google.com/document/d/1KZ-ANko-qn5CYmY13m4OVJXAYjLaS1VP-c64Pumipq8/edit?pli=1#heading=h.qyk8qz8ez37b
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