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Asked: 2026-06-10T19:10:02+00:00

This is my JVM parameters: > /usr/local/java/bin/java -Xloggc:log/gc.log -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -XX:PermSize=64m -XX:MaxPermSize=64m -Xss128K -server

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This is my JVM parameters:

> /usr/local/java/bin/java -Xloggc:log/gc.log -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -XX:PermSize=64m -XX:MaxPermSize=64m -Xss128K -server -Xmn1024m -Xms3027m -Xmx3027m -Dresin.home=/usr/local/resin

I using Resin,the up is Resin start JVM parameters,the following is my GC output when I using jstat -gcutil pid 1000 1000

   S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT   

  0.00   1.60  46.21  25.62  21.69  72639  941.082    31    0.275  941.357

  1.51   0.00  51.91  25.63  21.69  72640  941.093    31    0.275  941.368

  0.00   1.87  62.96  25.64  21.69  72641  941.104    31    0.275  941.379

  1.51   0.00  86.39  25.65  21.69  72642  941.114    31    0.275  941.389

  0.00   1.56  94.28  25.65  21.69  72643  941.126    31    0.275  941.401

  0.00   1.45   5.03  25.67  21.69  72645  941.146    31    0.275  941.421

  1.74   0.00  18.76  25.68  21.69  72646  941.158    31    0.275  941.433

  0.00   1.85  37.51  25.69  21.69  72647  941.169    31    0.275  941.443

  1.59   0.00  53.58  25.70  21.69  72648  941.180    31    0.275  941.455

  0.00   1.74  74.02  25.71  21.69  72649  941.192    31    0.275  941.467

We can find the minor GC about once per second,I feel it’s very frequent,because my new Edanz size is 1g.so why so frequent or that’s a normal thing?

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1 Answer

  1. Editorial Team

    Either you Eden size is not 1 GB or you are creating an incredible about of garbage. As you don’t appear to be setting your Eden size, suspects it much smaller than you think.

    Try using jstat -gccause instead to see the sizes.

    I suspect you have been reading http://www.caucho.com/resin-3.0/performance/jvm-tuning.xtp which incorrectly states that -Xmn sets the Eden space. 😉

    The -Xmx option sets the maximum total heap size (young and old)

    The -Xmn option sets the size of the young generation which consists of the Eden space and two survivor spaces. As your survivor spaces don’t appear to be very full, I suspect they account for most of the 1 G of young generation.

    http://www.oracle.com/technetwork/java/javase/tech/exactoptions-jsp-141536.html

    Try setting the -XX:SurvivorRatio= to something like 10 and most of the 1 GB will be Eden space.

    http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html

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