zookeeper-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Michael Han <h...@apache.org>
Subject Re: [Help Wanted] Will zookeeper merge change events?
Date Tue, 23 Oct 2018 22:24:48 GMT
Hi Jun,

>> will it only notify the client of the 100th event or all events from 2 -
100 will be notified?

All events will be notified. Each watched event will be materialized as a
server side response and on client side, each watched event will be
processed individually.

Depend on how your set watches and the scale of watch (e.g. a single client
watch a million znode, or a million clients watch a single znode, or a mix
of both), there could be thundering herd effects if multiple watches are
triggered.


On Tue, Oct 23, 2018 at 4:40 AM Jun Liu <liujun@apache.org> wrote:

> Hi,
>
> Our project, Dubbo[1], an RPC framework, has using Zookeeper as the
> service discovery and config centre for a long time. Recently, we received
> performance reports from users when a batch of service instances restart at
> the same time. One thing I can figure out is that the change of one
> instance status will trigger one change event to the Registry Centre -
> Zookeeper, so, 100 instances will trigger 100 change events at the same
> time.
>
> AFAIK, Zookeeper client uses a single thread to handle all these events
> one by one, if that is the case, will zookeeper merge the following events
> and only notify once? For example, if the Zookeeper client is handling the
> 1st event, the rest 2-100 events are created, when the 1st event is
> finished, will it only notify the client of the 100th event or all events
> from 2 - 100 will be notified?
>
> 1. https://github.com/apache/incubator-dubbo
>
> Best regards,
> Jun from Apache Dubbo (Incubating)
>
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message