51628.286: [GC 51628.288: [ParNew: 1843200K->204800K(1843200K),21.3196040 secs] 5177730K->3743415K(7987200K),21.3217870 secs] [Times: user=1.38 sys=0.33,real=21.32 secs]
我理解这样的输出：年轻一代的大小是1843200K.前一代规模为1843200K,规模为204800K.集合持续21.3秒.
通常,我们的年轻一代收藏品持续1秒.在哪些情况下,yg收藏品持续了很久？
我们的JVM参数：
-server -verbose:gc -XX:+PrintGCTimeStamps -XX:+PrintGCDetails -XX:NewRatio=3 -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+UseCMSCompactAtFullCollection -XX:CMSInitiatingOccupancyFraction=60 -XX:MaxPermSize=256m -Xss512k -Xms8000m -Xmx8000m
java版本：
java version "1.6.0_29" Java(TM) SE Runtime Environment (build 1.6.0_29-b11) Java HotSpot(TM) 64-Bit Server VM (build 20.4-b02,mixed mode)
谢谢,
马塞尔
解决方法
此外,我们有多台VM在同一物理机上运行.确保您没有为所有虚拟机分配更多的内存,而不是在服务器上具有物理内存.
有关更多信息,请参阅Tuning the Memory Management System,section Setting the Heap Size(我的重点)：
Command line options: -Xms: -Xmx:
The heap size has an impact on allocation speed,garbage collection
frequency and garbage collection times. A small heap will become full
quickly and must be garbage collected more often. It is also prone to
more fragmentation,making object allocation slower. A large heap
introduces a slight overhead in garbage collection times. A heap that is larger than the available physical memory in the system must be paged out to disk,which leads to long access times or even application freezes,especially during garbage collection.
