Notes: Computation

Parallel vs Concurrent

Multi core, multiple tasks happening at a single point in time.
Single core, quickly switching between multiple tasks where only one task is happening at a single point in time.


CPU Bound
CPU is working through the problem.
I/O Bound
CPU is waiting for the data.

Threads (Concurrency)

Native Threads (1:1)
1 app thread = 1 OS thread.
Green Threads (N:M)
Several virtual threads map to a pool of OS threads.

Efficiency != Performance

Efficiency with Algorithms, Performance with Data Structures - Chandler Carruth

Efficiency = Algorithms

Efficiency is doing less work to get the same result.

Performance = Data Structures

Data Structures allow the CPU pipeline to perform better.

Message Passing

n=5, bounded, buffered, asynchronous
Future / Promise
n=1, bounded, buffered, asynchronous
Channels, Actor model
n=0, bounded, unbuffered, synchronous