Hi,

We did a stress test for our kylin server with 100 concurrent queies. It worked 
fine at first. But after 1 day, we can't query kylin any more, and there is log 
like "query has been running 80396  seconds", many "bad queries" were hung 
there. Hbase nodes were still alive, and the cubes and jobs could still be 
listed on the pages. To make sure whether it was the problem of hbase, I 
restarted hbase, and did a new query, no log from region server shown hbase 
received the query, for as we know, a successful query will create log like 
"Klin Coprocessor start; Klin Coprocessor aggregation done". And from the 
kylin.log, there were still queries hung.  

Do you know what caused the problem? In our opnion, it may be because:
1. We use kylin 1.1 on hbase 1.0.1.1(I modified the hbase version in pom.xml to 
create the package);
2. The tomcat max threads setting, we didn't modify any setting in tomcat;
3. Kylin's problem.

BTW, we read the code of BadQueryDetector, and it seems a query thread will be 
killed only when low available memory and 5 minutes lasted. We doubt may be 
this is not very reasonable.

Best Regards,
 
George/倪春恩
Software Engineer/软件工程师
Mobile:+86-13501723787| Fax:+8610-56842040
北京明略软件系统有限公司(www.mininglamp.com)
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F4,1#,Zhongmei Construction Group Plaza,398# Zhongdong Road,Changping 
District,Beijing,102218
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