configuration - cassandra write, multi thread -

i have problem cassandra 2.1.8 , i'm using cassandra-driver-core-2.1.6.jar i'm using 10 of thread doing insert cassandra 50000 rows(each thread) @ same time. but, thread slow. thread time different others.( time, takes insert 50000 rows). think need tuning on cassandra.

this part of code.

for(int = 0; < 50000; i++) {         bind = statement.bind("key" + + thread + j, param);         resultsetfuture = session.executeasync(bind);         if(i % 1000 == 0) {             futures.add(resultsetfuture);             for(resultsetfuture future : futures) {                 future.getuninterruptibly();             }         }     } 

can me? please.... should need change settings?

1) how many cassandra nodes have?

2) doing when run thate code?

3) what's schema?

4) how many requests per second think should able do?

5) basing answer #4 on?