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https://issues.apache.org/jira/browse/HBASE-25510?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17266600#comment-17266600
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Viraj Jasani commented on HBASE-25510:
--------------------------------------
Thanks for filing this Jira [~zhengzhuobinzzb]. Since you have raised PR and
you are working on this, I have provided Jira contributor access to you and
assigned this Jira to you. Going forward, you will be able to assign Jira to
yourself.
> Optimize TableName.valueOf from O(n) to O(1). We can get benefits when the
> number of tables in the cluster is greater than dozens
> ----------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-25510
> URL: https://issues.apache.org/jira/browse/HBASE-25510
> Project: HBase
> Issue Type: Improvement
> Components: master, Replication
> Affects Versions: 1.2.12, 1.4.13, 2.4.1
> Reporter: zhuobin zheng
> Assignee: zhuobin zheng
> Priority: Major
> Attachments: optimiz_benchmark, origin_benchmark, stucks-profile-info
>
>
> Now, TableName.valueOf will try to find TableName Object in cache
> linearly(code show as below). So it is too slow when we has thousands of
> tables on cluster.
> {code:java}
> // code placeholder
> for (TableName tn : tableCache) {
> if (Bytes.equals(tn.getQualifier(), qns) && Bytes.equals(tn.getNamespace(),
> bns)) {
> return tn;
> }
> }{code}
> I try to store the object in the hash table, so it can look up more quickly.
> code like this
> {code:java}
> // code placeholder
> TableName oldTable = tableCache.get(nameAsStr);{code}
>
> In our cluster which has tens thousands of tables. (Most of that is KYLIN
> table).
> We found that in the following two cases, the TableName.valueOf method will
> severely restrict our performance.
>
> Common premise: tens of thousands table in cluster
> cause: TableName.valueOf with low performance. (because we need to traverse
> all caches linearly)
>
> Case1. Replication
> premise1: one of table write with high qps, small value, Non-batch request.
> cause too much wal entry
> premise2: deserialize WAL Entry includes calling the TableName.valueOf method.
> Cause: Replicat Stuck. A lot of WAL files pile up.
>
> Case2. Active Master Start up
> NamespaceStateManager init should init all RegionInfo, and regioninfo init
> will call TableName.valueOf. It will cost some time if TableName.valueOf is
> slow.
>
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