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.
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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. It makes “what happens next” a really hard problem. That means you’ll often be stuck with limited capabilties, unless you write your own libraries or hack up existing ones. When we want to write data, for example, the usual pattern looks like: 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.
What exactly is it that made this thing the snake oil blicking the week? That no common means have been invented for that is what I’m sad about. It splits sequential algorithms up libeveht multiple callbacks with manually managed shared state. It uses greenlets to make code written sychronously run asynchronously behind the scenes.
Underlying output buffer object EventBuffer. That can be extremely bad for latency.
Constructing signal events
It isn’t snake oil – it works and works well in the right situations. Thanks to you and ajross, this really helps. RoboTeddy on Jan 11, If I had to speculate: Again, event stuff has been here forever, and clearly is appropriate for some tasks. When the buffer event is freed, close the underlying transport. Decide that we want to write some data to a connection; put that data in a buffer.
Event-based code obscures control flow, as you note; threaded code is subject to very subtle and hard-to-reproduce bugs. Fork-per-connection sequential is simple and pretty fast, but it does have its poortable it works fine for a simple webapp, but writing a high-performance IRC server that way will be rather painful. Also, the maintainer only updates sporadically, but I’ve never had libeventt problems with it.
This will nkn an underlying socket, free an underlying buffer event, etc.
An event occured during a read operation on the bufferevent. See the other flags for which event it was. If I had to speculate: An event occured during a write operation on the bufferevent. Event programming is useful in that it effectively performs cooperative multitasking without the overhead of thread stack space.
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 nrtwork your maximum connection count.
Fast portable non-blocking network programming with Libevent
RoboTeddy on Jan 11, Libevent is rock solid — it handles the event loop for memcache, among other things. Numeric file descriptor associated with the buffer event. Usually an application wants to perform some amount of data buffering in addition to just responding to events. Remember how much we wrote, and if we still have more data to write, wait for the connection to become writable again.
One problem with using an event dispatcher like libevent is that libraries that make their own blocking calls won’t cooperate.
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.
But most apps don’t fall into those categories, and I’m not getting any of that vibe from this. Multiple requests can be running in parallel without fully blocking each other.
It’s too bad that no standard method for a asynchronous events has been developed for Unix in general.
Most of it is still relevant, though it was written before scary parallel SMP became common 8-way is routine for a server these days. For more information on what the error was, call EventUtil:: It’s frombut is a good overview of well-understood techniques.
When we want to write data, for example, the usual pattern looks like:. It was used heavily in the 90’s when threaded multiplexing was still new and threads were expensiveand it works well enough. We do a lot of network programming, so it would be unthinkable for any performance intensive application to do blocking calls exclusively. Hacker News new comments show ask jobs submit.
programmng JoachimSchipper on Jan 11, It seems like a good fit for both the indexing hubs and the storage nodes, and it pairs well with Lua’s coroutines. Normally represents a bound socket. It feels sort of like writing in continuation-passing-style. Within a single thread they do serialize, but only by the length of your callbacks.
PHP: EventBufferEvent – Manual
Sequential code is very readable, but not efficient at scale. Libevent is rock solid — it handles the event loop for memcache, among other things. Also for python is pyevent, which works pretty well. I submitted the link.
Where I work, there’s one single library for concurrency, and every program or toolkit uses it. It’s not a standard part of Unix, of course, but it seems reasonably portable. 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