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I think that you spend far too much time presupposing that I don’t know what I am talking about, when I choose to use an analogy that strikes you as “a little odd.” (I regret to inform you that you are not the most knowledgeable individual on this planet; nor am I.) And you certainly waste not a single opportunity to criticize my simple homilies. No, obviously, a select() loop is not the same thing as “asynchronous I/O,” which is simply the idea of starting an I/O operation without blocking the requesting process or thread until it completes. But both it and “the telephone switchboard operator” are a simple but effective illustration of the idea of being able to do many things “at once” with but a single thread or process (say...) being responsible for all. As you very-correctly pointed out in this thread, “signaling” a process in Unix/Linux is a very disruptive thing to do and it almost always causes severe timing-related problems that might well not be reproducible ... except, of course, in production, where they will invariably happen every time. A unit of work, be it an asynchronous I/O request or a select() packet or even a light on a telephone switchboard, is not equivalent to (nor does it in any way require...) a dedicated thread or process. A very simple sequential event-handling procedure .. of which select() is, of course, probably the most common example .. can service a great number of “simultaneous” requests and, since the internal logic is not parallel, a whole phalanx of otherwise messy issues (mutexes and locks and so forth) simply vanish. Tell ’ya what ... try this sometime ... read my posts (or for that matter, just about anyone else’s that you have lately responded to), and don’t respond at all. Don’t correct them. In particular, don’t teach them the error of their ways. If you want a web-site where your word is king, simply set up one of your own. Add your own comments, but if someone says something that’s technically not the perfect way to say it, just let their own words rest in peace. In reply to Re^6: how did blocking IO become such a problem?
by sundialsvc4
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