-server-Xms2048m-Xmx2048m-Xmn512m-XX:MaxPermSize=256m-Xss128k-XX:+UseConcMarkSweepGC-XX:ParallelCMSThreads=2-XX:CMSInitiatingOccupancyFraction=75-XX:+UseCMSCompactAtFullCollection-XX:CMSFullGCsBeforeCompaction=5-XX:+UseParNewGC-XX:ParallelGCThreads=2上述参数说明