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https://issues.apache.org/jira/browse/CASSANDRA-15241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16902084#comment-16902084
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Benedict commented on CASSANDRA-15241:
--------------------------------------
bq. One problem was that the task field was not guaranteed under the JMM to
ever see modifications to its contents
So, thinking on this more - this is probably not actually the case. We always
invoke a virtual method on executing the task (a virtual method on the task
itself), which should require that the state of the class is fully visible (not
to other threads, but we can depend on implementation details here). If the
task were to inspect this field, it should expect to see the value prior to its
invocation. So this is probably fine, and we can revert the changes I
suggested here.
> Virtual table to expose current running queries
> -----------------------------------------------
>
> Key: CASSANDRA-15241
> URL: https://issues.apache.org/jira/browse/CASSANDRA-15241
> Project: Cassandra
> Issue Type: New Feature
> Components: Feature/Virtual Tables
> Reporter: Chris Lohfink
> Assignee: Chris Lohfink
> Priority: Normal
>
> Expose current running queries and their duration.
> {code}cqlsh> select * from system_views.queries;
> thread_id | duration_micros | task
> ------------------------------+-----------------+---------------------------------------------------------------------------------
> Native-Transport-Requests-17 | 6325 | QUERY
> select * from system_views.queries; [pageSize = 100]
> Native-Transport-Requests-4 | 14681 | EXECUTE
> f4115f91190d4acf09e452637f1f2444 with 0 values at consistency LOCAL_ONE
> Native-Transport-Requests-6 | 14678 | EXECUTE
> f4115f91190d4acf09e452637f1f2444 with 0 values at consistency LOCAL_ONE
> ReadStage-10 | 16535 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-13 | 16535 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-14 | 16535 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-19 | 11861 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-20 | 11861 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-22 | 7279 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-23 | 4716 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-5 | 16535 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-7 | 16535 |
> SELECT * FROM basic.wide1 LIMIT 5000
> ReadStage-8 | 16535 |
> SELECT * FROM basic.wide1 LIMIT 5000{code}
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