[jira] [Created] (CASSANDRA-7371) DELETEs get lost

["Robert Stupp (JIRA)" <ji...@apache.org>]

Robert Stupp created CASSANDRA-7371:
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             Summary: DELETEs get lost
                 Key: CASSANDRA-7371
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7371
             Project: Cassandra
          Issue Type: Bug
          Components: Core
         Environment: 2.1 git branch since merge commit 029cd403172f8cc1b96f0828c8e1f8f6d57c0bcc ("Fix rare potential NPE in HHOM page size calculation")
            Reporter: Robert Stupp
            Priority: Blocker
             Fix For: 2.1.0


The mentioned commit (merged to 2.1 from 1.2 via 2.0) introduced a bug which is not easy to reproduce:

Workload description:
- One INSERT into a table
- multiple concurrent SELECTs against different tables (one select returns a result)
- One UPDATE against the same table as the INSERT
- (same) multiple concurrent SELECTs against different tables (one select returns a result)
- One DELETE against the same table as the INSERT
- (same) multiple concurrent SELECTs against different tables

Expected is that the last bunch of SELECTs returns no result. But since commit SHA  the DELETE gets not processed.
To clarify - the DELETE is not delayed - it is not executed at all.

Checked against a single node C* "cluster".

The above works with 2.0.8 and against 2.1.0-* - but not C* code since git commit 029cd403172f8cc1b96f0828c8e1f8f6d57c0bcc ("Fix rare potential NPE in HHOM page size calculation") from June, 5th.

I am not sure whether this bug also occurs in 1.2 or 2.0 branches (didn't check that).

It is not always reproducible - approx 1 of 50 tries run into this issue.

If you have difficulties in finding the reason, I can provide a unit test for that.



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