GC Tuning

[Joseph]

Hi Poonam,

Thank you for your valuable time.

Using the flags mentioned below ,I am trying to tune the nosql database HBase .Due to this reason I have no control over the source code . I will update the flags and back with the updated logs.

Thank you

Regards
Joseph




From: Poonam Bajaj Parhar [mailto:poonam.bajaj at oracle.com]
Sent: Friday, September 18, 2015 12:09 AM
To: Joseph James; hotspot-gc-use at openjdk.java.net
Subject: Re: GC Tuning

Hello Joseph,

>From the GC logs, all the G1 evacuation pauses are under 100ms of pause time goal. However, there are System.gc() invoked Full GCs that are taking longer time.

62.730: [GC pause (young), 0.02510300 secs]

...

64.287: [Full GC (System.gc()) 175M->98M(2048M), 0.2183040 secs]

 [Times: user=0.26 sys=0.01, real=0.22 secs]

64.509: [Full GC (System.gc()) 98M->98M(2048M), 0.1928990 secs]

 [Times: user=0.24 sys=0.00, real=0.20 secs]

64.704: [Full GC (System.gc()) 98M->98M(2048M), 0.1893760 secs]

 [Times: user=0.25 sys=0.00, real=0.19 secs]

64.896: [Full GC (System.gc()) 98M->97M(2048M), 0.2001590 secs]

 [Times: user=0.25 sys=0.00, real=0.20 secs]

65.098: [Full GC (System.gc()) 98M->97M(2048M), 0.1874640 secs]

 [Times: user=0.24 sys=0.00, real=0.19 secs]

66.818: [Full GC (System.gc()) 185M->99M(2048M), 0.2137830 secs]

 [Times: user=0.27 sys=0.00, real=0.22 secs]

73.240: [GC pause (young), 0.02516600 secs]
Please check your application code to see if these System.gc() invocations are intentional. You may also disable these using -XX:+DisableExplicitGC option.

Thanks,
Poonam
On 9/17/2015 6:02 AM, Joseph wrote:
Hi ,

I am Joseph. I am trying to tune performance of  our server .I run server with following g1 gc options.

Maximum heap allocated to server is 5GB.

" -XX:+UseG1GC -XX:MaxGCPauseMillis=100 -XX:ParallelGCThreads=4 -XX:InitiatingHeapOccupancyPercent=65 -XX:+ParallelRefProcEnabled -XX:-ResizePLAB -Xloggc:/var/log/hbase/gc-hbase.log -XX:+PrintGCDetails -XX:+PrintAdaptiveSizePolicy -XX:+PrintGCTimeStamps"

The gc logs resulted with above gc flags are attached with the mail.How to reduce garbage pause time in our server.

Thank you for your valuble time


Regards,
Joseph


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