JVM parameter Description

Heap = Young Generation (new) + Senior generation (old)

Young generation = Eden and survivor*2

-xmx2048m Maximum Heap Size

-xms2048m Initial Heap Size

-xmn1024m Young Generation Size

-xss1m the stack size per thread

-xx:permsize=256m Initial persistent generation size

-xx:maxpermsize=256m Maximum persistent generation size

-XX:+USEPARNEWGC set Young on behalf of the parallel collection

-XX:+USECONCMARKSWEEPGC set old age on behalf of concurrent collection

-xx:+cmsparallelremarkenabled Decrease Mark Pause

Ratio of-xx:survivorratio=8 Eden/survivor

-xx:maxtenuringthreshold=15 This parameter is used to control how many times an object can go through minor GC before being promoted to an old generation

On the-xx:cmsinitiatingoccupancyfraction=75 CMS heap, use 75% to start the CMS collection.

-xx:+usecmsinitiatingoccupancyonly only start the CMS collection using the manually defined initialization definition

-xx:+usecompressedoops

Most HotSpot JVM in the last year has had it on by default. This option is allows references to being 32-bit in a 64-bit JVM and access close to up to + GB of heap. (more than 32-bit pointers can) (You can has near unlimited off heap memory as well). This can save a significant amount of memory and potentially improve performance.

If you want the use of this option I suggest your update to a version which had it on by default as there could have been a good Reason, such as bugs, why it wasn ' t enabled previously. Try Java 6 Update or Java 7 update 5.

In short, don ' t turn it on, and use a version which have it on by default.

-xx:+printgcdetails Print more detailed GC information

-xx:+printgcdatestamps Print GC timestamp, relative to the time the application started

-xx:+printclasshistogram Print the histogram of the class, with the Kill-3 PID will print

-xloggc:log/gc.log Print GC information to the specified file can be set to the absolute path.

This article is from the "Cock Silk counter attack" blog, please make sure to keep this source http://5731674.blog.51cto.com/5721674/1763986

JVM parameter Description