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From "Joshua McKenzie (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-8907) Raise GCInspector alerts to WARN
Date Fri, 04 Sep 2015 12:57:46 GMT


Joshua McKenzie commented on CASSANDRA-8907:

bq. any unreasonably high GC
While I *personally * agree that 1000ms is unreasonably high, I'd also say that I think 500ms
is unreasonably high. Or 250ms. Unfortunately there's no single right answer for a default
value for GC duration on a node and I was thinking we err on the side of Least Astonishment.

That being said I'm not married to the idea and I'm core dev, not in ops. For the folks in
ops reading this - what are your thoughts on a default at 1k vs. disabled? cc [~jeromatron]
/ [~johnny15676] / [~ahattrell]

> Raise GCInspector alerts to WARN
> --------------------------------
>                 Key: CASSANDRA-8907
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Adam Hattrell
>              Labels: patch
>         Attachments: cassnadra-8907.patch
> I'm fairly regularly running into folks wondering why their applications are reporting
down nodes.  Yet, they report, when they grepped the logs they have no WARN or ERRORs listed.
> Nine times out of ten, when I look through the logs we see a ton of ParNew or CMS gc
pauses occurring similar to the following:
> INFO [ScheduledTasks:1] 2013-03-07 18:44:46,795 (line 122) GC for ConcurrentMarkSweep:
1835 ms for 3 collections, 2606015656 used; max is 10611589120
> INFO [ScheduledTasks:1] 2013-03-07 19:45:08,029 (line 122) GC for ParNew:
9866 ms for 8 collections, 2910124308 used; max is 6358564864
> To my mind these should be WARN's as they have the potential to be significantly impacting
the clusters performance as a whole.

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