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From "Ma Gang (JIRA)" <>
Subject [jira] [Created] (KYLIN-1872) Make query visible and interruptible, improve server's stablility
Date Mon, 11 Jul 2016 06:28:11 GMT
Ma Gang created KYLIN-1872:

             Summary: Make query visible and interruptible, improve server's stablility
                 Key: KYLIN-1872
             Project: Kylin
          Issue Type: Improvement
          Components: Query Engine
            Reporter: Ma Gang
            Assignee: Ma Gang

1. Large query result will break kylin server, for example: select * from fact_table. Even
when properties "kylin.query.scan.threshold" and "kylin.query.mem.budget" are set properly,
OOM still happens, because the hbase rpc thread is not interrupted, the result will continually
go to kylin server. And server will run OOM quickly when there are multiple such queries.
2. Tow many slow queries will occupy all tomcat threads, and make server unresponsed.
3. There's no corelation id for a specified query, so it is hard to find the rpc log for a
specified query, if there are too many queries running concurrently.

1. Interrupt the rpc thread and main query thread when return result size larger than the
config limit size.
2. Make query visible. Admin can view all running queries, and detail of each query. 
   Split the query into following steps:
   1) sql parse
   2) cube plan 
   3) query cache
   4) multiple cube segment query
      a. for each segment request, have muliple endpoint range request.
      b. for each endpoint range request, have multiple coprocessor request.
      c. for eache coprocessor request, have multiple region server rpc.

   Admin can view the startTime/endTime of each step, and the thread stack trace if the step
is running.
3. Add query id as corelation id in the rpc log.
4. Admin can interrupt a running query, to release the thread, memory, etc.

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