Libevent is pretty cool, but it is not “fast” for all applications. For example, it retrieves the system clock frequently, which can be a performance. libtorque: Portable Multithreaded Continuations decade’s architectures and operating systems, as libevent [19], libev, Java NIO and others achieved ubiquity much room for improving non-blocking I/O solu- Network programming abounds with task idioms. .. this approach could be the fastest path to true zero- . I want to know how to use libevent l.4,especially the use of http. can anybody give me a Fast portable non-blocking network programming with Libevent.

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I’ve been reading about multiplexing asynchronous IO because I’m writing a distributed filesystem of sorts. Simpler netdork are good enough sometimes, though. An error occurred during a bufferevent operation. Sure, but libraries underneath you have to cooperate for you to use it to the fullest potential. It wasn’t too long ago when people were excited about fork-for-each-connection servers, though at least half of it was “OMG Unix system calls from Ruby” from people who probably don’t know C.

Fast portable non-blocking network programming with Libevent | Hacker News

If I had to speculate: It was used heavily in the 90’s when threaded multiplexing was still new and threads were expensiveand it works well enough. There are plenty of services that won’t ever need to handle more than a couple simultaneous connections, and that way you don’t need to bother with asynchronous IO. It’s frombut is a good overview of well-understood techniques. It makes “what happens next” a really hard problem. Neywork more information on what the error was, call EventUtil:: Lots of huge sites rely on memcache, for example, which would suck if it didn’t use event-based IO.


PHP: EventBufferEvent – Manual

One problem with using an event dispatcher like libevent is that libraries that make their own nwtwork calls won’t cooperate. It uses greenlets to make code written sychronously run asynchronously behind the scenes. Normally represents a bound socket. Thanks to you and ajross, this really helps. This will close an underlying socket, free an underlying buffer event, etc.

Constructing signal events

Equals to NULL portbale, if there is no file descriptor socket associated with the buffer event. JoachimSchipper on Jan 11, Fork-per-connection sequential is simple and pretty fast, but it does have its limits it works fine for a simple webapp, but writing a high-performance IRC server that way will be rather painful.

Numeric file descriptor associated with the buffer event. I submitted the link. Where I work, there’s one single library for concurrency, and every program or toolkit uses it.

On the other end, say you run a thread per socket – that’s not effective as the memory usage for reserving thread stack space will limit your maximum connection count. Multiple requests can be running in parallel without fully blocking each other. Underlying output buffer object EventBuffer. It seems that a lot of people sincerely believe that this stuff is “easier” or “better” just because it has the fancy new Spicy Event Sauce.

The EventBufferEvent class

Also, I’m not convinced that the “nasty state bugs” from reorganizing around an event loop are necessarily worse than the ones that come from using threads with shared state.

The short answer may very well be no, since it somewhat depends on the programming language one chooses to use. Also, the maintainer only updates sporadically, but I’ve never had real problems with it. It’s too bad that no standard method for a asynchronous events has been developed for Unix in general.


Sequential code is very readable, but not efficient at scale. And the truth isn’t like that at all, and in fact these are truths that we’ve all known for years now What exactly is it that made this thing the snake oil of the week?

Fast portable non-blocking network programming with Libevent wangafu. Instead of regular events, which give callbacks when the underlying ntework is ready to be read or written, a buffer event invokes its user-supplied callbacks when it has read or written enough data.

EOF Got an end-of-file indication on the buffer event. Remember how much we wrote, and if we still have more data to write, wait for the connection to become writable again. Again, event stuff has been here forever, and clearly is appropriate for some tasks.

RoboTeddy on Jan 11, It splits sequential algorithms up into multiple callbacks with manually managed shared state. It’s not a standard part of Unix, of course, but it seems reasonably portable. Edit Report a Bug. This is hardly a new idea, in fact it’s very well-traveled ground. When the buffer event is freed, close the underlying transport.

That means you’ll often be stuck with limited capabilties, unless you write your own libraries or hack up existing ones. An event occured during a read operation on the bufferevent. See the other flags for which event it was. Also, some observations on server design from Jeff Darcy http: