Go - prevent race condition

• 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