jvm优化

一、用JMeter创建100个线程对指定url进行压力测试。初始状态，吞吐量为8.7/s





二、参考java程序性能优化，在tomcat的catalina.bat新增配置。重新设置堆大小和永久区大小、禁用显示GC、去掉类校验、使用并行回收收集器代替串行收集器、使用CMS回收器、设置较大的survivior区，努力将对象预留在新生代、将CMS的Full GC触发的阈值设置为78%，即当老年代使用到78%时，才触发Full GC。吞吐率提高到9.4/s

set CATALINA_OPTS=%CATALINA_OPTS% "-XX:+PrintGCDetails"
set CATALINA_OPTS=%CATALINA_OPTS% "-Xmx512M"
set CATALINA_OPTS=%CATALINA_OPTS% "-Xms512M"
set CATALINA_OPTS=%CATALINA_OPTS% "-XX:PermSize=64M"
set CATALINA_OPTS=%CATALINA_OPTS% "-XX:MaxPermSize=64M"
set CATALINA_OPTS=%CATALINA_OPTS% "-XX:+DisableExplicitGC"
set CATALINA_OPTS=%CATALINA_OPTS% "-Xverify:none"
set CATALINA_OPTS=%CATALINA_OPTS% "-XX:+UseConcMarkSweepGC"
set CATALINA_OPTS=%CATALINA_OPTS% "-XX:ParallelCMSThreads=8"
set CATALINA_OPTS=%CATALINA_OPTS% -XX:+UseCMSCompactAtFullCollection
set CATALINA_OPTS=%CATALINA_OPTS% -XX:CMSFullGCsBeforeCompaction=0
set CATALINA_OPTS=%CATALINA_OPTS% -XX:CMSInitiatingOccupancyFraction=78
set CATALINA_OPTS=%CATALINA_OPTS% -XX:SoftRefLRUPolicyMSPerMB=0
set CATALINA_OPTS=%CATALINA_OPTS% -XX:+CMSParallelRemarkEnabled
set CATALINA_OPTS=%CATALINA_OPTS% -XX:SurvivorRatio=1
set CATALINA_OPTS=%CATALINA_OPTS% -XX:+UseParNewGC