Ma Gang created KYLIN-1872:
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Summary: Make query visible and interruptible, improve server's
stablility
Key: KYLIN-1872
URL: https://issues.apache.org/jira/browse/KYLIN-1872
Project: Kylin
Issue Type: Improvement
Components: Query Engine
Reporter: Ma Gang
Assignee: Ma Gang
Problem:
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.
Solution:
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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