[
https://issues.apache.org/jira/browse/HBASE-7590?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13619684#comment-13619684
]
Nicolas Liochon commented on HBASE-7590:
----------------------------------------
Here is the proposal for the release note:
{panel}
This allows to setup a multicast connection between the master and the hbase
clients. With the feature on, when a regionserver is marked as dead by the
master, the master sends as well a multicast message that will make the hbase
client to disconnect immediately from the dead server instead of waiting for a
socket timeout. Specifically, this allows to set hbase.rpc.timeout to larger
values (like 5 minutes) without impacting the MTTR: without this, even if the
dead regionserver data is now available on another server, the client stays on
the dead one, waiting for an answer that will never come. It's a multicast
message, hence cheap, scalable, but unreliable. For this reason, the master
sends the information 5 times, to allow the hbase client to miss a message.
This feature is NOT activated by default. To activate it, add to your
hbase-site.xml:
<property>
<name>hbase.status.publisher.class</name>
<value>org.apache.hadoop.hbase.master.ClusterStatusPublisher$MulticastPublisher</value>
</property>
<property>
<name>hbase.status.listener.class</name>
<value>org.apache.hadoop.hbase.client.ClusterStatusListener$MulticastListener</value>
</property>
You can as well configure the ip address and port used with the following
setting:
<property>
<name>hbase.status.multicast.address.ip</name>
<value>226.1.1.3</value>
</property>
<property>
<name>hbase.status.multicast.address.port</name>
<value>6100</value>
</property>
{panel}
> Add a costless notifications mechanism from master to regionservers & clients
> -----------------------------------------------------------------------------
>
> Key: HBASE-7590
> URL: https://issues.apache.org/jira/browse/HBASE-7590
> Project: HBase
> Issue Type: Bug
> Components: Client, master, regionserver
> Affects Versions: 0.96.0
> Reporter: Nicolas Liochon
> Assignee: Nicolas Liochon
> Fix For: 0.95.0, 0.96.0
>
> Attachments: 7590.inprogress.patch, 7590.v12.patch, 7590.v12.patch,
> 7590.v13.patch, 7590.v1.patch, 7590.v1-rebased.patch, 7590.v2.patch,
> 7590.v3.patch, 7590.v5.patch, 7590.v5.patch
>
>
> t would be very useful to add a mechanism to distribute some information to
> the clients and regionservers. Especially It would be useful to know globally
> (regionservers + clients apps) that some regionservers are dead. This would
> allow:
> - to lower the load on the system, without clients using staled information
> and going on dead machines
> - to make the recovery faster from a client point of view. It's common to use
> large timeouts on the client side, so the client may need a lot of time
> before declaring a region server dead and trying another one. If the client
> receives the information separatly about a region server states, it can take
> the right decision, and continue/stop to wait accordingly.
> We can also send more information, for example instructions like 'slow down'
> to instruct the client to increase the retries delay and so on.
> Technically, the master could send this information. To lower the load on
> the system, we should:
> - have a multicast communication (i.e. the master does not have to connect to
> all servers by tcp), with once packet every 10 seconds or so.
> - receivers should not depend on this: if the information is available great.
> If not, it should not break anything.
> - it should be optional.
> So at the end we would have a thread in the master sending a protobuf message
> about the dead servers on a multicast socket. If the socket is not
> configured, it does not do anything. On the client side, when we receive an
> information that a node is dead, we refresh the cache about it.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
