C # Parallel programming

Chapter II command-style data parallelism

Several parallel types:

Data parallelism

Task parallelism

Pipeline

Under the System.threading.tasks.parallel

Parallel.For

Parallel.ForEach (can be customized Parytitioner)

Parallel.Invoke

1. Parallel.Invoke

No specific execution order

Interleaved Concurrency: Logical cores implement parallel artifacts through time-slice mechanisms and fast context switches

Concurrency: Not explained

Hot spots: Potentially parallel code

Speedup: Serial execution time/parallel execution time

2. Parallel.For

Each iteration is assigned to a thread as a task

The upper bounds of the iteration range are less than, so it is necessary to add a

3. Parallel.ForEach

Can be partitioned through the partitioner partition, with each iteration processing a partition,tuple<int,int>

Exit

ParallelLoopState

Break: Does not end immediately, execution is less than the current iteration of the content

Stop: Exit as soon as possible

Parallelloopresult

IsCompleted Cycle Complete

! IsCompleted &&! Lowestbreakiteration.hasvalue Stop Termination

! IsCompleted && Lowestbreakiteration.hasvalue Break terminated

AggregateException

. InnerExceptions Internal Exception Collection

ParallelOptions

Maxdegreeoofparallelism degree of parallelism

CancellationToken Cancel Token

TaskScheduler Task Scheduler

Chapter III Command-parallel task parallelism

System.Threading.Tasks.Task

A task represents an asynchronous operation and does not target a thread

State

Taskstatus.created Initial State

. Waitingforactivation the initial state of tasks that depend on other tasks

. Waitingtorun the initial state of a task created by taskfactory.startnew

. Cancelled

. Faulted

. Runtocompletion

Task. Start ()

Task. Wait () Waits also have overloads that are timed out

Task.waitall ()

The Task.TaskFactory.StartNew method can pass arguments to the CancellationToken, or taskcreationoptions

Taskcreationoption

. AttachedToParent associated with a parent task

. None default behavior

. Longrunning long-time operation, the scheduler can be coarse-grained operation, generally more than one second

. Preferfairness tells the scheduler that earlier scheduled tasks are executed earlier

Task. ContinueWith Continuation Tasks

Taskcontinuationoptions operation or condition

C # Parallel programming