Go - prevent race condition

Initialize variables when package initialization phase, it will happen before main function. And don't modify those variables after initialization.

Avoid modifying variables by multiple goroutine => Every goroutine take care of different variable modification.
Dont communicate by sharing memory, share memory by communicating
Can pass variable address to pipeline to confine goroutine to modify variable
Confine variables to different stages
Allow many goroutines to access one variable, but only one access variable at a time