2.1.5 - thinking concurrently

Question 1

parallel processing

Answer 1

Requires multiple processors, each executing different instructions simultaneously, with the goal of speeding up computations.

Question 2

concurrent processing

Answer 2

Several processes are running, with each in turn being given a slice of processor time. Only one processor is necessary.

Question 3

reasons for concurrent processing

Answer 3

• The number of tasks completed in a given time is increased.
• Time that would be wasted by the processor waiting on the user is used on another task.

Question 4

disadvantages of concurrent processing

Answer 4

• safety: Possibility of corrupting the consistent state of a program.
• liveness: Tasks can suspend and wait on each other indefinitely, known as deadlock.
• resource consumption: Threads can consume resources in regards to scheduling, context-switching and synchronisation.

Question 5

advantages of concurrent processes

Answer 5

• reactive programming: Users are able to interact with applications while other tasks are running.
• availability of services: A long-running task won’t delay short-running ones.
• parallelism: A complex program can make use of multicore and/or multiprocessor systems.
• controllability: A task requiring preconditions to proceed can be suspended and easily resumed later.