groovyc Example.groovy && java -cp "groovy-all-2.4.13.jar;." Example

Example.groovy

import java.util.concurrent.ConcurrentHashMap

def a = new ConcurrentHashMap();

for (int i = 0; i < 1000000; i++) {
  a.put(UUID.randomUUID().toString(), UUID.randomUUID().toString())
}
println ((Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / (1024 * 1024))

def t = new Thread(new Runnable() {
  @Override
  void run() {
    def rs = a.keySet().collect{
      def s = System.currentTimeMillis()
      a.get(it)
      def e = System.currentTimeMillis()
      e - s
    }
    println "finish ${rs.size()}"
    println "${rs.min()} - ${rs.max()} - ${rs.sort().get((int)Math.floor(rs.size() / 99))}"
  }
})
t.start()
for (int i = 0; i < 10000; i++) {
  print "-"
  a.put(UUID.randomUUID().toString(), UUID.randomUUID().toString())
}

println ((Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / (1024 * 1024))