OK, I think I miss read old generation gc issue. the line I quoted shows
the old generation region mem size after a young gc. it should be expected
after a young generation gc because some surviving objects are promoted
from young to survival and from survivor to old.

Jinyuan (Jack) Zhou

On Mon, Dec 22, 2014 at 7:28 PM, Jinyuan Zhou <[email protected]>
wrote:

> Hi,
> I like to share my experience and in the same time hope I can get some
> tips.
>
> The query was run against  an index with about 700 million  documents.
> Two things happens,
> 1. The node run  this query crashed. It is the node configured not to
> proccess data.
>
> 2. The data nodes start crazy on GC. eventually old generation gc cannot
> reduce the heep usage and the nodes becomes unresponsive.  in some cases.
> OLD generation gc even increased size of the heap:
>
>
> *2014-12-20 07:21:03,370][WARN ][monitor.jvm              ] [******]
> [gc][young][2796041][224976] duration [1.1s], collections [1]/[1.3s], total
> [1.1s]/[3.4h], memory [21.5gb]->[21.2gb]/[29.8gb], all_pools {[young]
> [1.4gb]->[3.4mb]/[1.4gb]}{[survivor]
> [191.3mb]->[191.3mb]/[191.3mb]}{[old] [19.9gb]->[21gb]/[28.1gb]}*
>
>
> It is a bad query by itself. But I expected ES cluster handles it
> gracefully. It does throw this exception:
>
> * Caused by: org.elasticsearch.common.breaker.CircuitBreakingException:
> [FIELDDATA] Data too large, data for [_uid] would be larger than limit of
> [19206989414 <%5B19206989414>/17.8gb]*
> I guess ES stopped at some point because  field data exceeds the default
> limit. But it is too late to stop the query that caused heap memory issue.
> I am wondering if there is any obvious wrong with my ES cluster
> configuration.
> I have 5 box eah with 125 ram and 32 cores. I deploy two data nodes on
> each of them the heap fixed at 31G  and configuration is favor bulk
> ingesting. I actually saw above 60+K document ingesting through put per
> second.  It was working fine until that query comes.
>
> Thanks,
>
> Jack
>
>
>
>
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