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https://issues.apache.org/jira/browse/TAJO-1397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14630835#comment-14630835
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ASF GitHub Bot commented on TAJO-1397:
--------------------------------------
Github user jihoonson commented on a diff in the pull request:
https://github.com/apache/tajo/pull/608#discussion_r34864411
--- Diff: tajo-core/src/main/java/org/apache/tajo/master/QueryManager.java
---
@@ -178,35 +174,29 @@ public QueryInfo scheduleQuery(Session session,
QueryContext queryContext, Strin
QueryInProgress queryInProgress = new QueryInProgress(masterContext,
session, queryContext, queryId, sql,
jsonExpr, plan);
- synchronized (submittedQueries) {
- queryInProgress.getQueryInfo().setQueryMaster("");
- submittedQueries.put(queryInProgress.getQueryId(), queryInProgress);
- }
+ queryInProgress.getQueryInfo().setQueryMaster("");
--- End diff --
How about defining a constant to represent an empty query master host?
> Resource allocation should be fine grained.
> -------------------------------------------
>
> Key: TAJO-1397
> URL: https://issues.apache.org/jira/browse/TAJO-1397
> Project: Tajo
> Issue Type: Improvement
> Components: QueryMaster, resource manager, Worker
> Reporter: Hyunsik Choi
> Assignee: Jinho Kim
> Fix For: 0.11.0
>
> Attachments: ResoruceSequence.jpg, TAJO-1397.patch,
> TAJO-1397_2.patch, old_resource_circuit.png, resource_circuit.png
>
>
> See the comment:
> https://issues.apache.org/jira/browse/TAJO-540?focusedCommentId=14359478&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14359478
> From the discussion in TAJO-540
> {quote}
> In general, query (or job) scheduler aims at the maximum resource
> utilization. For multi-tenancy, we also need to consider the fairness for
> multiple users (or queries). BTW, the maximum resource utilization and
> fairness are usually conflict to each other in many cases. To mitigate this
> problem, many scheduler seems to use preemption approach.
> In this point, our resource and scheduler system has the following problems:
> * A query exclusively uses allocated resources at the first time until the
> query is completed or failed.
> * There is no mechanism to deallocate resources during query processing.
> * Preempt is also not allowed.
> To achieve the multi tenancy, we should change our resource circulation.
> Especially, resource allocation must be fine grained instead of per query.
> So, I'll create a jira issue to change the resource circulation. We have to
> do this issue firstly in my opinion. If we achieve this, implementing
> multi-tenant scheduler would be much easier than now. It would be a good
> starting point of this issue.
> {quote}
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