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From "Stefania (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-7392) Abort in-progress queries that time out
Date Thu, 17 Sep 2015 03:35:46 GMT


Stefania commented on CASSANDRA-7392:

bq. When you mean doesn't notice it was aborted, you mean it completes one of these subqueries
and then is issued the next one? It would notice while processing an individual query regardless
of CAS or lazySet. They both become globally visible at the same speed so CAS isn't going
to do better.

I've read [this documentation|]
according to which the updated value might not be visible to other threads until some other
volatile write or synchronizing action occurs and it occurred to me that the worker thread
may carry on working on the query even though the query has been aborted by the monitoring
thread. This was after a couple of hours debugging a flacky dtest by the way, but it turns
out the problem with the dtest was something unrelated. How can you be sure that they both
become globally visible at the same speed? It seems to contradict with what I've read, do
you have any other documentation source?

bq. Some other databases log every slow query so this is fine as a starting point.

So we want to log all queries or are we OK with just the first 50? Basically is there anything
else that should be done?

> Abort in-progress queries that time out
> ---------------------------------------
>                 Key: CASSANDRA-7392
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Stefania
>            Priority: Critical
>             Fix For: 3.x
> Currently we drop queries that time out before we get to them (because node is overloaded)
but not queries that time out while being processed.  (Particularly common for index queries
on data that shouldn't be indexed.)  Adding the latter and logging when we have to interrupt
one gets us a poor man's "slow query log" for free.

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