JVM Tuning Parameter memo

Environment: 4G memory, dual-core CPU optimization parameter settings:-Xms2048M initial heap memory size-Xmx2048M maximum heap memory size-Xmn512M New Generation size (Eden zone and two vor zones)-XX: permSize = 256 M initial permanent generation size-XX: MaxPermSize = 256 M maximum permanent generation size-XX: SurvivorRatio = 8 ratio of the Eden and Survivor areas in the new generation-XX: maxTenuringThreshold = 7 Number of times that an object is replicated in the same vor area-XX: GCTimeRatio = 19. Set the percentage of the garbage collection time to the running time. The formula is 1/(1 + n) -Xnoclassgc: Disable garbage collection of Persistent Object-XX: + DisableExplicitGC to disable System. gc ()-XX: + UseParNewGC set the new generation to parallel collection-XX: + UseConcMarkSweepGC use CMS Memory collection-XX: + CMSPermGenSweepingEnabled use CMS Memory to collect persistent generation-XX: + when UseCMSCompactAtFullCollection is full gc, It compresses the old generation to eliminate memory fragments-XX: CMSFullGCsBeforeCompaction = 0 how many times after full gc is performed for memory compression, 0 indicates that every time the-XX: + CMSClassUnloadingEnabled space is not enough, you can unload the class to release the space for FULL GC-XX: CMSInitiatingOccupancyFraction = 70 memory use 70% start CMS collection