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https://issues.apache.org/jira/browse/SOLR-11522?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16647457#comment-16647457
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Noble Paul edited comment on SOLR-11522 at 10/12/18 6:20 AM:
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Ideally, it should just be {{get(..)}}.
but as this class is implemented by a million other classes there is likely to
be a conflict. so I went with {{_get(..)}}.
The broad philosophy is that Solr has embraced JSON for everything (even some
of the JUnit tests are driven by JSON).
We need to have an in-memory representation of JSON which is
* memory efficient and as little overhead as possible
* streaming . Use as little memory as possible
* can be serialized to any of the supported outputs with ease .(supports
Javabin etc too)
* No concrete classes . hence {{MapWriter}}, {{IteratorWriter}} interfaces
If a class implements {{MapWriter}}, most likely it is a deeply nested Object.
. The most common operation that you can perform is to query that object with a
proper path like {{a/b/c[4]/d}} . Looking up a {{MapWriter}} is usually an
operation with a complexity of {{O(n)}} and no new Objects are created in the
process. So, it is pretty fast. The best part is the readability it offers to
our tests
Using a string path is OK for JUnit tests but it leads to creation of
unnecessary objects. If we use it in other places, we can't afford to create
new {{String}} objects. That's why I created an equivalent method
{{get(List<String>)}} which doesn't create new Objects.
The alternative was to use a {{Utils#getObjectByPath()}} method . It was
definitely ugly.
was (Author: noble.paul):
Ideally, it should just be {{get(..)}}.
but as this class is implemented by a million other classes there is likely to
be a conflict. so I went with {{_get(..)}}.
The broad philosophy is that Solr has embraced JSON for everything (even some
of the JUnit tests are driven by JSON).
We need to have a cheap in-memory representation of JSON which is
* memory efficient and as little overhead as possible
* streaming . Use as little memory as possible
* can be serialized to any of the supported outputs with ease .(supports
Javabin too)
* No concrete classes . hence {{MapWriter}}, {{IteratorWriter}} interfaces
If a class implements {{MapWriter}}, most likely it is a deeply nested Object.
. The most common operation that you can perform is to query that object with a
proper path like {{a/b/c[4]/d}} . Looking up a MapWriter is usually an
operation with a complexity of {{O\(n)}} and no new Objects are created in the
process. So, it is pretty fast. The best part is the readability it offers to
our tests
Using a string path is OK for JUnit tests but it leads to creation of
unnecessary objects. If we use it in other places, we can't afford to create
new {{String}} objects. That's why I created an equivalent method
{{get(List<String>)}} which doesn't create new Objects.
The alternative was to use a {{Utils#getObjectByPath()}} method . It was
definitely ugly.
> Suggestions/recommendations to rebalance replicas
> -------------------------------------------------
>
> Key: SOLR-11522
> URL: https://issues.apache.org/jira/browse/SOLR-11522
> Project: Solr
> Issue Type: Sub-task
> Security Level: Public(Default Security Level. Issues are Public)
> Components: AutoScaling
> Reporter: Noble Paul
> Priority: Major
>
> It is possible that a cluster is unbalanced even if it is not breaking any of
> the policy rules. Some nodes may have very little load while some others may
> be heavily loaded. So, it is possible to move replicas around so that the
> load is more evenly distributed. This is going to be driven by preferences.
> The way we arrive at these suggestions is going to be as follows
> # Sort the nodes according to the given preferences
> # Choose a replica from the most loaded node ({{source-node}})
> # try adding them to the least loaded node ({{target-node}})
> # See if it breaks any policy rules. If yes , try another {{target-node}}
> (go to #3)
> # If no policy rules are being broken, present this as a {{suggestion}} .
> The suggestion contains the following information
> #* The {{source-node}} and {{target-node}} names
> #* The actual v2 command that can be run to effect the operation
> # Go to step #1
> # Do this until the a replicas can be moved in such a way that the {{target
> node}} is more loaded than the {{source-node}}
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