chap1

Parallelism = simultaneous execution(doing things at once.)

Concurrency = the composition of independently executing processes.(dealing things at once.)

Do not communicate by sharing memory; instead, share memory by communicating.

other language = when concurrent threads need to share data, a lock is applied to the memory.

• race conditions, memory management etc.

Go = send variable from one thread to another.

• The receiver will wait till the value reaches.

• The “waiting” -> synchronisation between threads when data is being exchanged.

An analogy

Concurrent: Mouse, keyboard, display, and disk drivers.

Parallel: Vector dot product.

https://talks.golang.org/2012/waza.slide#1

Goroutines

go before a function call -> goroutine

Channel

a connection between two goroutines

unbufferedchannel := make(chan string) 
bufferedchannel := make(chan int, 20)

unbuffered channel = no capacity = require both goroutines to be ready to make any exchange

• When there is a sender-goroutine, but no receiver-goroutine, the channel will lock the sender and make it wait, vice versa.

• One can not happen without the other.

• Synchronization is inherent.

buffered channel = with capacity

• If the buffer is full or empty, a buffered channel will behave very much like an unbuffered channel.

• A sender will be locked if the buffered channel is full.

• A receiver will be locked if the buffered channel is empty.