关于G1的Java 7(JDK 7)垃圾收集和文档 [英] Java 7 (JDK 7) garbage collection and documentation on G1
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问题描述
我的问题:
- G1是默认收集器在Java 7中,如果不是如何激活G1?
- g1在Java7中有什么可选设置?
- 是否有任何其他更改在Java 7中收集器如 cms 或并行收集器?
- 哪里可以找到有关Java 7垃圾收集的良好文档?
解决方案
在我的Java 1.7版安装中,G1垃圾收集器不是默认设置。 0_01。您可以使用一些额外的命令行选项来查看自己:
> java -XX:+ PrintCommandLineFlags -XX:+ PrintGCDetails -version
-XX:InitialHeapSize = 132304640 -XX:MaxHeapSize = 2116874240 -XX:ParallelGCThreads = 4 -XX:+ PrintCommandLineFlags -XX:+ PrintGCDetails -XX:+ UseCompressedOops -XX:-UseLargePagesIndividualAllocation -XX:+ UseParallelGC
Java版本1.7.0_01
Java™SE运行时环境(build 1.7.0_01-b08)
Java HotSpot™64位服务器VM(构建21.1-b02,混合模式)
堆
PSYoungGen总计37696K,使用1293K [0x00000007d5eb0000,0x00000007d88c0000,0x0000000800000000)
eden空间32320K,使用4%[0x00000007d5eb0000,0x00000007d5ff3408 ,0x00000007d7e40000)
from space 5376K,0%used [0x00000007d8380000,0x00000007d8380000,0x00000007d88c0000)
to space 5376K,0%used [0x00000007d7e40000,0x00000007d7e40000,0x00000007d8380000)
PSOldGen total 86144K,used 0K [ 0x0000000781c00000,0x0000000787020000,0x00000007d5eb0000)
对象空间86144K,使用0%[0x0000000781c00000,0x0000000781c0 0000,0x0000000787020000)
PSPermGen总计21248K,使用2032K [0x000000077ca00000,0x000000077dec0000,0x0000000781c00000)
对象空间21248K,使用9%[0x000000077ca00000,0x000000077cbfc288,0x000000077dec0000)
不过,您无需启用实验性选项即可开启G1收藏夹。
> java -XX:+ PrintCommandLineFlags -XX:+ PrintGCDetails -XX:+ UseG1GC -version
-XX:InitialHeapSize = 132304640 -XX:MaxHeapSize = 2116874240 -XX:+ PrintCommandLineFlags -XX:+ PrintGCDetails -XX:+ UseCompressedOops - XX:+ UseG1GC -XX:-UseLargePagesIndividualAllocation
java版本1.7.0_01
Java™SE运行时环境(build 1.7.0_01-b08)
Java HotSpot™64-位服务器虚拟机(构建21.1-b02,混合模式)
堆
垃圾优先堆总计130048K,使用0K [0x000000077ca00000,0x0000000784900000,0x00000007fae00000)
区域大小1024K,1个青年(1024K) ,0幸存者(0K)
压缩烫发电池总数20480K,使用2032K [0x00000007fae00000,0x00000007fc200000,0x0000000800000000)
空间20480K,使用9%[0x00000007fae00000,0x00000007faffc288,0x00000007faffc400,0x00000007fc200000)
否共享空间配置。
我不知道你在哪里可以找到任何好的文档。
Java 7 has been out for a while now, but I cannot find any good resources on the configuration of the garbage collectors, specifically the new G1 collector.
My questions:
- Is G1 the default collector in Java 7 and if not how do I activate G1?
- What optional settings does g1 have in Java7?
- Were there any changes made to other collectors like cms or the parallel collector in Java 7?
- Where can I find good documentation on garbage collection in Java 7?
解决方案The G1 garbage collector is not the default in my installation of Java, version 1.7.0_01. You can see for yourself by using with some extra command line options:
> java -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -version -XX:InitialHeapSize=132304640 -XX:MaxHeapSize=2116874240 -XX:ParallelGCThreads=4 -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -XX:+UseCompressedOops -XX:-UseLargePagesIndividualAllocation -XX:+UseParallelGC java version "1.7.0_01" Java(TM) SE Runtime Environment (build 1.7.0_01-b08) Java HotSpot(TM) 64-Bit Server VM (build 21.1-b02, mixed mode) Heap PSYoungGen total 37696K, used 1293K [0x00000007d5eb0000, 0x00000007d88c0000, 0x0000000800000000) eden space 32320K, 4% used [0x00000007d5eb0000,0x00000007d5ff3408,0x00000007d7e40000) from space 5376K, 0% used [0x00000007d8380000,0x00000007d8380000,0x00000007d88c0000) to space 5376K, 0% used [0x00000007d7e40000,0x00000007d7e40000,0x00000007d8380000) PSOldGen total 86144K, used 0K [0x0000000781c00000, 0x0000000787020000, 0x00000007d5eb0000) object space 86144K, 0% used [0x0000000781c00000,0x0000000781c00000,0x0000000787020000) PSPermGen total 21248K, used 2032K [0x000000077ca00000, 0x000000077dec0000, 0x0000000781c00000) object space 21248K, 9% used [0x000000077ca00000,0x000000077cbfc288,0x000000077dec0000)
You don't need to enable experimental options to turn on the G1 collector any more, though:
> java -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -XX:+UseG1GC -version -XX:InitialHeapSize=132304640 -XX:MaxHeapSize=2116874240 -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -XX:+UseCompressedOops -XX:+UseG1GC -XX:-UseLargePagesIndividualAllocation java version "1.7.0_01" Java(TM) SE Runtime Environment (build 1.7.0_01-b08) Java HotSpot(TM) 64-Bit Server VM (build 21.1-b02, mixed mode) Heap garbage-first heap total 130048K, used 0K [0x000000077ca00000, 0x0000000784900000, 0x00000007fae00000) region size 1024K, 1 young (1024K), 0 survivors (0K) compacting perm gen total 20480K, used 2032K [0x00000007fae00000, 0x00000007fc200000, 0x0000000800000000) the space 20480K, 9% used [0x00000007fae00000, 0x00000007faffc288, 0x00000007faffc400, 0x00000007fc200000) No shared spaces configured.
I don't know where you can find any good documentation.
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