python 编程中的术语“阻塞”是什么意思？
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What does the term "blocking" mean in programming?
提问by alfredo
Could someone provide a layman definition and use case?
有人可以提供一个外行的定义和用例吗？
回答by T.J. Crowder
"Blocking" means that the caller waits until the callee finishes its processing. For instance, a "blocking read" from a socket waits until there is data to return; a "non-blocking" read does not, it just returns an indication (usually a count) of whether there was something read.
“阻塞”意味着调用者等待被调用者完成其处理。例如，来自套接字的“阻塞读取”一直等到有数据返回；“非阻塞”读取不会，它只是返回一个指示（通常是一个计数）是否有读取的东西。
You hear the term mostly around APIs that access resources that don't necessarily require CPU attention -- I/O, for instance. You also hear it in multi-threading: A call from Thread A to Thread B might be designed to "block" (hold up Thread A) until Thread B achieves the relevant state to process or at least accept the request. (The most obvious example there being "join", which usually means "I, Thread A, want to wait until Thread B has terminated" -- you use that when exiting a multi-threaded program.)
您听到的这个术语主要是关于访问不一定需要 CPU 关注的资源的 API —— 例如，I/O。您还可以在多线程中听到：从线程 A 到线程 B 的调用可能被设计为“阻塞”（阻止线程 A），直到线程 B 达到相关状态来处理或至少接受请求。（最明显的例子是“加入”，这通常意味着“我，线程 A，想要等到线程 B 终止”——你在退出多线程程序时使用它。）
回答by friederbluemle
In simple words: If you call a function that stops the program from continuing to run until the user has performed some action (or some other action that your program is not controlling), this call is called a blocking call.
简而言之：如果您调用一个函数，该函数会阻止程序继续运行，直到用户执行某些操作（或您的程序未控制的其他操作），此调用称为阻塞调用。
