全GC当许多对象年龄＆gt; = 15但不是长寿命的对象时？

发布于 2025-02-08 02:44:43 字数 964 浏览 0 评论 0原文

我的Java应用程序经常使用完整的GC 。

通过分析GC日志，我发现有许多年龄的物体= 15。我想许多物体在达到MaxteningThreshold = 15后已将其晋升为老年，这导致终身一代越来越大。最后，全GC 发生了。

但是，借助gceasy工具，我发现旧一代还通过完整的GC回收了很多垃圾。大约2390-＆gt; 800。

原因是什么？是因为有很多年龄的物体＆gt; 15不属于终身一代？也许他们的年龄= 16,17,18？但是不是长寿命的对象吗？

这是我的JVM配置：

-Xmx6g
-Xms6g
-XX:NewRatio=1
-XX:+UseConcMarkSweepGC
-XX:CMSInitiatingOccupancyFraction=75
-XX:+UseCMSInitiatingOccupancyOnly
-XX:MaxTenuringThreshold=15
-XX:+ParallelRefProcEnabled
-XX:+CMSParallelRemarkEnabled
-XX:+UseCMSCompactAtFullCollection
-XX:+HeapDumpOnOutOfMemoryError
-XX:MetaspaceSize=512m
-XX:MaxMetaspaceSize=512m
-XX:+PrintGCDetails
-XX:+PrintGCDateStamps
-Xloggc:/export/Logs/gc.log
-XX:+PrintTenuringDistribution
-XX:SurvivorRatio=4

年龄分布

/a>

在这种情况下，如何调整JVM？

谢谢你！

原文

My java applications frequently use full GC.

By analyzing gc log, I found that there were many objects with age >= 15. I guess that many objects were promoted to the old age after reaching maxtenuringthreshold=15, which led to the tenured generation becoming larger and larger. Finally, full GC occurred.

But with the help of gceasy tool, I found that the old generation also recycled a lot of garbage through full GC. About 2390 -> 800.

What is the reason? Is it because there are many objects with age > 15 that do not belong to the tenured generation? Maybe their age =16,17,18? But not long-live objects?

Here is my JVM configuration:

-Xmx6g
-Xms6g
-XX:NewRatio=1
-XX:+UseConcMarkSweepGC
-XX:CMSInitiatingOccupancyFraction=75
-XX:+UseCMSInitiatingOccupancyOnly
-XX:MaxTenuringThreshold=15
-XX:+ParallelRefProcEnabled
-XX:+CMSParallelRemarkEnabled
-XX:+UseCMSCompactAtFullCollection
-XX:+HeapDumpOnOutOfMemoryError
-XX:MetaspaceSize=512m
-XX:MaxMetaspaceSize=512m
-XX:+PrintGCDetails
-XX:+PrintGCDateStamps
-Xloggc:/export/Logs/gc.log
-XX:+PrintTenuringDistribution
-XX:SurvivorRatio=4

Age distribution

Old generation

Avg promotion rate

In this case, how can I tune the JVM?

Thank you!

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