ConcurrentWriter there is 1_3 goRoutines and we use them to convert struct to string.

HighConcurrentWriter count of goRoutines >=8 , we set a goRoutine for each file(just for writing) and other goRoutines will be used as worker pool for converting struct to string.

MultiGoroutinesWriter count of goRoutines ==4, we set a goRoutine for each file(converting and writing will be done in GoRoutine).

SequentialWriter There is 0 goRoutines and we write without using any goRoutine.