GC listener

[Ryan Gardner]

What kind of acceptable latency those who are doing the loadbalancer dance
looking for?

What is an unacceptable pause?

G1 can most definitely be tuned to avoid full gc's - I have a cluster of G1
apps that are running I think with 99.9% GC overhead and a median pause
time of 100ms with live data sets in the 34 GB range on 72 GB heaps. They
only do GC every couple of minutes which is why the overhead is so small -
and this is on a cache that probably churns through terabytes of garbage
every day (though done objects will live in heap for days - its finally a
use case that can torture many GC algorithms).

(By giving it plenty of extra heap, G1 is able to free up tons of regions
completely - its able to collect tens of  gigabytes of heap in normal
collections - and by tuning the collector the 99.9% pauses are kept below
our acceptable threshold)

G1 could have been faster than that but we had to gimp our CPU down because
the vendor licensed by CPU count and throwing more cores at it was
prohibitively expensive.

Taking an app out of a load balancer for GC seems like an outdated solution
to a problem that has better solutions really available now.
On Mar 22, 2014 9:36 AM, "Pas" <pasthelod at gmail.com> wrote:

> Hello!
>
> Just a quick For-Your-Information. At work we've implemented something
> very similar to the notification and System.gc scenario. (The only
> meaningful difference is that it's periodic, nothing
> dynamic-and-notification, there's a schedule and it blindly takes load off,
> fires GC, puts load back; and it uses the load-balancer's health-check
> functionality to signal that it's about to do a GC, so it would even work
> with HAproxy, Hipache or even with Nginx's 3rd party HealthCheckModule.)
> And I know of others who do this kind of dance on their backend.
>
> Cheers,
> Pas
>
>
> On Sat, Mar 22, 2014 at 12:40 PM, Milan Mimica <milan.mimica at infobip.com>wrote:
>
>> Milan Mimica, Software Engineer / Team Leader
>>
>> Milan Mimica, Software Engineer / Team Leader
>>
>> On 03/21/2014 06:44 PM, Peter B. Kessler wrote:
>>
>>> If you exclude yourself from the load balancer before the collection,
>>> you won't get any more work, won't do any more allocations, and won't cause
>>> the collection.  Wouldn't it be better to tune your collector to meet your
>>> deadlines while getting work done?
>>>
>>
>> Sure, application tuning is one way to go. I just want to know what my
>> options are.
>> A scheduled System.gc() with -XX:-ExplicitGCInvokesConcurrent also does
>> the job, but it's ugly.
>>
>>
>> _______________________________________________
>> hotspot-gc-use mailing list
>> hotspot-gc-use at openjdk.java.net
>> http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
>>
>
>
> _______________________________________________
> hotspot-gc-use mailing list
> hotspot-gc-use at openjdk.java.net
> http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/hotspot-gc-use/attachments/20140322/cc92a3f9/attachment.html>