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https://issues.apache.org/jira/browse/SLING-3321?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13879898#comment-13879898
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Bertrand Delacretaz commented on SLING-3321:
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Looks much better after [~cziegeler]'s http://svn.apache.org/r1560567 changes,
thanks!
I still get some timeouts with the while loop of the SLING-3321-log.txt
attachment and resultCacheTtlInMs set to 5000, but timeout results are not
cached anymore.
To avoid getting timeouts we might implement a policy to start executing a new
check if the cached result is older than say 50% of its time to live in cache,
but that's probably better considered together with a general mechanism to
refresh HC results regularly.
> Incorrect caching/timeout behavior with slow health check
> ---------------------------------------------------------
>
> Key: SLING-3321
> URL: https://issues.apache.org/jira/browse/SLING-3321
> Project: Sling
> Issue Type: Bug
> Components: Health Check
> Affects Versions: Health Check Core 1.0.8
> Reporter: Bertrand Delacretaz
> Assignee: Bertrand Delacretaz
> Attachments: SLING-3321-log.txt
>
>
> We might not need to fix this right now, just making a note of some tests I
> did with the SlowHealthCheckSample.
> By default SlowHealthCheckSample takes 1200-3700 msec to execute, and I have
> set the cache lifetime to 5 seconds.
> With these settings, executing the health check every second should always
> provide a result: even if a particular execute call takes more than the
> default 2 seconds execution timeout, an older cached result should still be
> available as 3700 (max execution time) + 1000 (execution period) is smaller
> than 5000 (time to live in cache)
> I'll attach an execution log which shows that this is not the case. I see two
> problems:
> # A result which times out is cached and reused, even though the actual
> execution might have finished in the meantime. We then get a timeout result
> and the actual result is thrown away. There's no " execution counter=2"
> result in my log for example.
> # There's no way to say "execute the health check, but if it times out use an
> older result if still valid". We might need an execution option for that, as
> you don't always want that.
> I think this is a realistic use case, checking external systems for example
> might have that kind of timing characteristics. I should be able to call the
> executor for such an HC every second, for example, and get a result every
> time,.
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