Specify the following configurations in the HBASE_REGIONSERVER_OPTS configuration option in the /conf/hbase-env.sh file:

-XX:+UseConcMarkSweepGC
-Xmn2500m (depends on MAX HEAP SIZE, but should not be less than 1g and more than 4g)
-XX:PermSize=128m 
-XX:MaxPermSize=128m 
-XX:SurvivorRatio=4 
-XX:CMSInitiatingOccupancyFraction=50 
-XX:+UseCMSInitiatingOccupancyOnly 
-XX:ErrorFile=/var/log/hbase/hs_err_pid%p.log 
-XX:+PrintGCDetails
-XX:+PrintGCDateStamps

Make sure that the block cache size and the memstore size combined do not significantly exceed 0.5*MAX_HEAP, which is defined in the HBASE_HEAP_SIZE configuration option of the /conf/hbase-env.sh file.