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https://issues.apache.org/jira/browse/MESOS-7688?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benjamin Mahler updated MESOS-7688:
-----------------------------------
Description:
Currently, during a failover the agents will (re-)register with the master.
While the master is recovering, the master may drop messages from the agents,
and so the agents must retry registration using a backoff mechanism. For large
clusters, there can be a lot of overhead in processing unnecessary retries from
the agents, given that these messages must be deserialized and contain all of
the task / executor information many times over.
In order to reduce this overhead, the idea is to avoid the need for agents to
blindly retry (re-)registration with the master. Two approaches for this are:
(1) Update the MasterInfo in ZK when the master is recovered. This is a bit of
an abuse of MasterInfo unfortunately, but the idea is for agents to only
(re-)register when they see that the master reaches a recovered state. Once
recovered, the master will not drop messages, and therefore agents only need to
retry when the connection breaks.
(2) Have the master reply with a retry message when it's in the recovering
state, so that agents get a clear signal that their messages were dropped. The
agents only retry when the connection breaks or they get a retry message. This
one is less optimal, because the master may have to process a lot of messages
and send retries, but once the master is recovered, the master will process
only a single (re-)registration from each agent. The number of
(re-)registrations that occur while the master is recovering can be reduced to
1 in this approach if the master sends the retry message only after the master
completes recovery.
was:
Currently, during a failover the agents will (re-)register with the master.
While the master is recovering, the master may drop messages from the agents,
and so the agents must retry registration using a backoff mechanism. For large
clusters, there can be a lot of overhead in processing unnecessary retries from
the agents, given that these messages must be deserialized and contain all of
the task / executor information many times over.
In order to reduce this overhead, the idea is to avoid the need for agents to
blindly retry (re-)registration with the master. Two approaches for this are:
(1) Update the MasterInfo in ZK when the master is recovered. This is a bit of
an abuse of MasterInfo unfortunately, but the idea is for agents to only
(re-)register when they see that the master reaches a recovered state. Once
recovered, the master will not drop messages, and therefore agents only need to
retry when the connection breaks.
(2) Have the master reply with a retry message when it's in the recovering
state, so that agents get a clear signal that their messages were dropped. This
one is less optimal, because the master may have to process a lot of messages
and send retries, but once the master is recovered, the master will process
only a single (re-)registration from each agent. Here, agents only retry when
the connection breaks or they get a retry message.
> Improve master failover performance by reducing unnecessary agent retries.
> --------------------------------------------------------------------------
>
> Key: MESOS-7688
> URL: https://issues.apache.org/jira/browse/MESOS-7688
> Project: Mesos
> Issue Type: Improvement
> Components: agent, master
> Reporter: Benjamin Mahler
> Labels: scalability
>
> Currently, during a failover the agents will (re-)register with the master.
> While the master is recovering, the master may drop messages from the agents,
> and so the agents must retry registration using a backoff mechanism. For
> large clusters, there can be a lot of overhead in processing unnecessary
> retries from the agents, given that these messages must be deserialized and
> contain all of the task / executor information many times over.
> In order to reduce this overhead, the idea is to avoid the need for agents to
> blindly retry (re-)registration with the master. Two approaches for this are:
> (1) Update the MasterInfo in ZK when the master is recovered. This is a bit
> of an abuse of MasterInfo unfortunately, but the idea is for agents to only
> (re-)register when they see that the master reaches a recovered state. Once
> recovered, the master will not drop messages, and therefore agents only need
> to retry when the connection breaks.
> (2) Have the master reply with a retry message when it's in the recovering
> state, so that agents get a clear signal that their messages were dropped.
> The agents only retry when the connection breaks or they get a retry message.
> This one is less optimal, because the master may have to process a lot of
> messages and send retries, but once the master is recovered, the master will
> process only a single (re-)registration from each agent. The number of
> (re-)registrations that occur while the master is recovering can be reduced
> to 1 in this approach if the master sends the retry message only after the
> master completes recovery.
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