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Concurrency

"time"

time.Sleep(timeAmount)

• stops/blocks the current thread execution for defined duration

Concurrency

Single thread execution

• step by step execution of the code
• later code has to wait until the earlier code finishes

Execute some functions in a separate thread >> CONCURRENCY

• main thread doesn't wait for these functions to finish
• next line of code is executed immediately

go keyword

go sendTicket(userTickets, firstName, lastName, email)

Problems

Main goroutine exits before a function had time to start & execute the code.
By default, main goroutine does not wait for other threads

Waitgroup

• waits for the launched goroutine to finish
• package "sync": provides synchronization functionality

var wg = sync.WaitGroup{}

...


// before starting another thread, specify how many threads the main goroutine will wait for
wg.Add(1)
go function()

• wg.Add(#): sets the number of goroutines to wait for
  • increases the counter by the provided number
• wg.Wait(): blocks until the WaitGroup counter is 0
• wg.DOne(): function tells main goroutine that it's done so there's no need to wait longer

How is Goroutine different?

• Go uses Green thread
  • green thread: abstraction of an actual thread
• managed by the go rutime
• only interacts with high level goroutines
  • no need to interact w/ kernels/hardware, etc.
• cheaper, lightweight
• easy communication between threads
  • Channels: built-in functionality for goroutines to talk with one another