ExecutorService slow multi thread performance

Question

I am trying to execute a simple calculation (it calls Math.random() 10000000 times). Surprisingly running it in simple method performs much faster than using Ex

Answer 1

Math.random() is synchronized. Kind of the whole point of synchronized is to slow things down so they don't collide. Use something that isn't synchronized and/or give each thread its own object to work with, like a new Random.