Use JDK8 and try G1 first, we saw lower GC pause under G1 especially in our
large memory environment
On Wednesday, November 29, 2017, 8:14:03 AM PST, eric wong
<[email protected]> wrote:
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From: eric wong <[email protected]>
To: [email protected]
Cc:
Bcc:
Date: Thu, 30 Nov 2017 00:07:47 +0800
Subject: Re: For Apache Hive HS2 , what is the largest heap size setting that
works well?
1）Long GC pause should has detailed reson, like InitialMark/Remark、Full GC due
to Concurrent Mode failure/Promotion failure。Please check it
2）CMS is nice and steady for our production. Please troubleshooting case by
case. G1 is just difficult to perceive.
3）You shouldupdate to JDK8 ，for one case，ConcurrentInitialMark is disabled as
default or just only can be sequenced in JDK7.
2017-11-29 15:14 GMT+08:00 Jörn Franke <[email protected]>:
I also recommend it you will have also performance improvements with JDK8 in
general (use the latest version). Keep also in mind that more and more big data
libraries etc will drop JDK7 support soon (Aside that JDK7 is anyway not
maintained anymore).
On 29. Nov 2017, at 01:31, Johannes Alberti <[email protected]> wrote:
Yes, I would recommend to go to Java 8 and give it a shot with G1 and report
back :)
Sent from my iPhone
On Nov 28, 2017, at 3:30 PM, Sharanya Santhanam <[email protected]> wrote:
HI Johannes ,
We are running on Java version jdk1.7.0_67 . We are using
ConcurrentMarkAndSweep. Would you recommend using G1GC ?
These are our current settings -XX:NewRatio=8 -XX:+UseParNewGC
-XX:-UseGCOverheadLimit -XX:PermSize=256m -Xloggc:<> -XX:HeapDumpPath=oom
-XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:ErrorFile=<log>/oom/hs2jvm
error%p.log -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5
-XX:GCLogFileSize=128M -XX:+CMSClassUnloadingEnabled
-XX:+CMSPermGenSweepingEnabled -XX:+HeapDumpOnOutOfMemoryErro r
-XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:MaxPermSize=1024m
-Xmx69427m -Xms128m -XX:MaxHeapFreeRatio=30 -XX:MinHeapFreeRatio=10
-XX:+UseParNewGC -XX:-UseGCOverheadLimit -XX:PermSize=256m
Thanks ,Sharanya
On Tue, Nov 28, 2017 at 2:19 PM, Johannes Alberti <[email protected]>
wrote:
Hi Sharanya,
Can you share your current GC settings and Java version. Are you using Java 8/9
w/ G1 already?
Regards,
Johannes
Sent from my iPhone
On Nov 28, 2017, at 12:57 PM, Sharanya Santhanam <[email protected]> wrote:
Hello ,
I am currently trying to upgrade hive version on our prod clusters form V1.2 to
v2.1 We also want to adopt HS2 on the new upgraded cluster. Earlier all queries
were submitted via Hive cli.
Would like to understand how large a single HS2 Heap size can be ? And is there
any formula to figure out the how many concurrent sessions I can support with
this particular heap setting?
We currently have a upper limit of supporting 300 concurrent sessions (
hive.server2.thrift.max.work er.threads=300). Based on this we set the max
heap size to 70 GB , but seeing many long GC pauses.
Would like to understand what is the industry standard for max HS2 Heap size.
Are there any recommendations on what JMV GC setting work best for supporting
such high number of concurrent sessions?
Thanks,Sharanya
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