并发编程是一个通用概念，即一个程序可以以未定义的完成顺序执行多个任务，并且这些任务可以同时执行，也可以不同时执行。

并行编程只是一种并发编程，其中这些任务运行在同时执行的线程上。

我真的不理解这里许多过于冗长的回答，这些回答似乎暗示并行编程和并行编程是不同的编程方法，它们并不重叠。

如果你在写一个并行程序，根据定义，你是在写一个并发程序的特殊情况。这些年来，术语似乎被不必要地混淆和复杂化了。

关于并发编程最好、最详细的报道之一是Joe Duffy所著的《Windows上的并发编程》一书。这本书定义了并发，然后继续解释各种操作系统资源，库等可用来编写“并行”程序，如。net中的任务并行库。

第5页:

并行性是使用并发性将操作分解为 粒度更细的组成部分，以便独立的部分可以运行 机器上的独立处理器"

同样，并行编程只是一种特殊类型的并发编程，其中多个线程/任务将同时运行。

PS 我一直不喜欢在编程中，并发和并行这两个词有如此多的含义。例:在编程之外的广阔世界里，“篮球比赛将并行进行”和“篮球比赛将并行进行”是完全相同的。

想象一下，在开发者大会上，他们在第一天宣传会议将“并行”运行，但第二天他们将“并发”运行，这是多么可笑的困惑。那会很搞笑的!

在编程中，并发是独立的组合 执行进程，而并行是同时执行 计算的(可能相关的)。 -安德鲁·格兰德

And

Concurrency is the composition of independently executing computations. Concurrency is a way to structure software, particularly as a way to write clean code that interacts well with the real world. It is not parallelism. Concurrency is not parallelism, although it enables parallelism. If you have only one processor, your program can still be concurrent but it cannot be parallel. On the other hand, a well-written concurrent program might run efficiently in parallel on a multiprocessor. That property could be important... - Rob Pike -

为了理解其中的区别，我强烈建议你去看看Rob Pike(Golang的创作者之一)的视频。并发不是并行

并发性和并行性源

在单个处理器上的多线程进程中，处理器可以在线程之间切换执行资源，从而实现并发执行。

在共享内存多处理器环境中的同一个多线程进程中，进程中的每个线程可以同时在单独的处理器上运行，从而导致并行执行。

当进程的线程数量与处理器数量相同或较少时，线程支持系统结合操作环境确保每个线程运行在不同的处理器上。

例如，在具有相同数量的线程和处理器的矩阵乘法中，每个线程(和每个处理器)计算结果的一行。

Concurrent programming regards operations that appear to overlap and is primarily concerned with the complexity that arises due to non-deterministic control flow. The quantitative costs associated with concurrent programs are typically both throughput and latency. Concurrent programs are often IO bound but not always, e.g. concurrent garbage collectors are entirely on-CPU. The pedagogical example of a concurrent program is a web crawler. This program initiates requests for web pages and accepts the responses concurrently as the results of the downloads become available, accumulating a set of pages that have already been visited. Control flow is non-deterministic because the responses are not necessarily received in the same order each time the program is run. This characteristic can make it very hard to debug concurrent programs. Some applications are fundamentally concurrent, e.g. web servers must handle client connections concurrently. Erlang, F# asynchronous workflows and Scala's Akka library are perhaps the most promising approaches to highly concurrent programming.

Multicore programming is a special case of parallel programming. Parallel programming concerns operations that are overlapped for the specific goal of improving throughput. The difficulties of concurrent programming are evaded by making control flow deterministic. Typically, programs spawn sets of child tasks that run in parallel and the parent task only continues once every subtask has finished. This makes parallel programs much easier to debug than concurrent programs. The hard part of parallel programming is performance optimization with respect to issues such as granularity and communication. The latter is still an issue in the context of multicores because there is a considerable cost associated with transferring data from one cache to another. Dense matrix-matrix multiply is a pedagogical example of parallel programming and it can be solved efficiently by using Straasen's divide-and-conquer algorithm and attacking the sub-problems in parallel. Cilk is perhaps the most promising approach for high-performance parallel programming on multicores and it has been adopted in both Intel's Threaded Building Blocks and Microsoft's Task Parallel Library (in .NET 4).

我的理解是:

1)并发-使用共享资源串联运行 2)使用不同的资源并行运行

所以你可以让两件事情同时发生，即使它们在点(2)聚集在一起，或者两件事情在整个执行的操作中占用相同的储备(1)。

我在一些博客上找到了这个内容。认为它是有用的和相关的。

并发性和并行性不是一回事。两个任务T1和T2是并发的，如果这两个任务的执行顺序不是预先确定的，

T1可以在T2之前执行和完成， T2可以在T1之前执行和完成， T1和T2可以在同一个时间实例中同时执行(并行性)， T1和T2可以交替执行， .．. 如果操作系统安排两个并发线程在一个单核非smt非cmp处理器上运行，您可能会得到并发性而不是并行性。并行在多核、多处理器或分布式系统上是可能的。

并发性通常被认为是程序的一种属性，是一个比并行性更普遍的概念。

来源:https://blogs.oracle.com/yuanlin/entry/concurrency_vs_parallelism_concurrent_programming