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https://issues.apache.org/jira/browse/RATIS-2524?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ivan Andika updated RATIS-2524:
-------------------------------
Description:
Currently each read will trigger a ReadIndex call.
One improvement is to batch reads together to a single ReadIndex call.
Rule: A ReadIndex result may only serve reads whose invocation happened before
the ReadIndex request is logically issued.
{code:java}
t1: read A arrives at follower
t2: read B arrives at follower
t3: follower sends one ReadIndex request for batch [A, B]
t4: leader processes ReadIndex and returns index I
t5: follower applies >= I
t6: A and B query local state and complete
{code}
It's not
{code:java}
t1: read A arrives
t2: follower sends ReadIndex request
t3: leader processes it
t4: read B arrives
t5: follower attaches B to A's ReadIndex result
{code}
This maybe can be implemented using batching window.
was:
Currently each read will trigger a ReadIndex call.
One improvement is to batch reads together to a single ReadIndex call.
Rule: A ReadIndex result may only serve reads whose invocation happened before
the ReadIndex request is logically issued.
{code:java}
t1: read A arrives at follower
t2: read B arrives at follower
t3: follower sends one ReadIndex request for batch [A, B]
t4: leader processes ReadIndex and returns index I
t5: follower applies >= I
t6: A and B query local state and complete
It's not
{code}
{code:java}
t1: read A arrives
t2: follower sends ReadIndex request
t3: leader processes it
t4: read B arrives
t5: follower attaches B to A's ReadIndex result
{code}
This maybe can be implemented using batching window.
> Implement ReadIndex coalescing
> ------------------------------
>
> Key: RATIS-2524
> URL: https://issues.apache.org/jira/browse/RATIS-2524
> Project: Ratis
> Issue Type: Improvement
> Reporter: Ivan Andika
> Assignee: Ivan Andika
> Priority: Major
>
> Currently each read will trigger a ReadIndex call.
> One improvement is to batch reads together to a single ReadIndex call.
> Rule: A ReadIndex result may only serve reads whose invocation happened
> before the ReadIndex request is logically issued.
> {code:java}
> t1: read A arrives at follower
> t2: read B arrives at follower
> t3: follower sends one ReadIndex request for batch [A, B]
> t4: leader processes ReadIndex and returns index I
> t5: follower applies >= I
> t6: A and B query local state and complete
> {code}
> It's not
> {code:java}
> t1: read A arrives
> t2: follower sends ReadIndex request
> t3: leader processes it
> t4: read B arrives
> t5: follower attaches B to A's ReadIndex result
> {code}
> This maybe can be implemented using batching window.
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