FAST PORTABLE NON BLOCKING NETWORK PROGRAMMING WITH LIBEVENT PDF
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 , 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.
|Published (Last):||27 April 2011|
|PDF File Size:||18.52 Mb|
|ePub File Size:||15.38 Mb|
|Price:||Free* [*Free Regsitration Required]|
When we want to write data, for example, the usual pattern looks netork This is hardly a new idea, in fact it’s very well-traveled ground. I know what you mean about an event loop complicating error handling from callbacks, though. What exactly is it that made this thing the snake libvent of the week? Libevent is rock solid — it handles the event loop for memcache, among other things.
Numeric file descriptor associated with the buffer event. Also, some observations on server design from Jeff Darcy http: We do a lot of network programming, so it would be unthinkable for any performance intensive application to do blocking calls exclusively. Where I work, there’s one single library for concurrency, and every program or toolkit uses it. Remember how much we wrote, and if we still have more data to write, wait for the connection to become writable again.
Multiple requests can be running in parallel without fully blocking each other.
Constructing signal events
It monkey-patches the python socket module with a version that automatically cooperates with libevent’s loop. And the truth isn’t like that at all, and in fact these are truths that we’ve all known for years now Wait for the connection to become writable Write as much of the data as we can Remember how much we wrote, and if we still have more data to write, wait for the connection to become writable again.
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.
An error occurred during a blockingg operation. OK, I gotta ask: It feels sort of like writing in continuation-passing-style. It splits sequential algorithms up into multiple callbacks with manually managed shared state. But most apps don’t fall into those categories, and I’m not getting any of that vibe from this.
Also, the maintainer only updates sporadically, but I’ve never had real problems with it. It was used heavily in the 90’s when threaded multiplexing was still new and threads were expensiveand it works well enough.
Blockign frombut is a good overview of well-understood techniques. Sure, but libraries underneath you have to cooperate for you to use it to the fullest potential.
But it’s difficult and error-prone. Again, event stuff has been here forever, and clearly is appropriate for some tasks. Underlying output buffer object EventBuffer. Thanks to you and ajross, this really helps. Event-based code obscures control flow, as you note; threaded code is subject to very subtle and hard-to-reproduce bugs. That means you’ll often be stuck with limited capabilties, unless you write your own libraries or hack up existing ones.
It isn’t snake oil – it works and works well in the right situations. It’s one of those things that I’ve read about different methods here and there, but I’ve never come across one good source that compared and contrasted the various techniques.
PHP: Constructing signal events – Manual
It uses greenlets to make code written sychronously run asynchronously behind the scenes. An event occured during a write operation on the bufferevent. But it’s a tradeoff: 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.
Anyway, I’m just curious Thanks.
PHP: EventBufferEvent – Manual
So if you’re writing the client handler for a database, or something like memcached, you need this technique whether you need an abstraction library is another argument An event occured during a read operation on the bufferevent. Simpler approaches are good enough sometimes, though.
It’s not a standard part of Unix, of course, but it seems reasonably portable.
Lots of huge sites rely on memcache, for example, which would suck if it didn’t use event-based IO. Instead of regular events, which give callbacks when the underlying transport is ready to be read or written, a buffer event invokes its user-supplied callbacks when it has read or written enough data.
When we want to write data, for example, the usual pattern looks like:. Event programming is useful in that it effectively performs cooperative multitasking without the overhead of thread stack space. Underlying input buffer object EventBuffer.