Reading a single file with Multiple Thread: should speed up?

Question

I\'m reading a file which conatins 500000 rows. I\'m testing to see how multiple thread speed up the process....

private void multiThreadRead(int num){

             


        

Answer 1

The reason you are seeing a slow down when reading in parallel is because the magnetic hard disk head needs to seek the next read position (taking about 5ms) for each thread. Thus, reading with multiple threads effectively bounces the disk between seeks, slowing it down. The only recommended way to read a file from a single disk is to read sequentially with one thread.