Well blocking IO means that a given thread cannot do anything more until the IO is fully received (in the case of sockets this wait could be a long time). Non-blocking IO means an IO request is queued straight away and the function returns. The actual IO is then processed at some later point by … Read more
In InputStreams, read() calls are said to be “blocking” method calls. That means that if no data is available at the time of the method call, the method will wait for data to be made available. The available() method tells you how many bytes can be read until the read() call will block the execution … Read more
The methods performBlock: and performBlockAndWait: are used to send messages to your NSManagedObjectContext instance if the MOC was initialized using NSPrivateQueueConcurrencyType or NSMainQueueConcurrencyType. If you do anything with one of these context types, such as setting the persistent store or saving changes, you do it in a block. performBlock: will add the block to the … Read more
Node is asynchronous by nature, and that’s what’s great about it, so you really shouldn’t be blocking the thread, but as this seems to be for a project controlling LED’s, I’ll post a workaraound anyway, even if it’s not a very good one and shouldn’t be used (seriously). A while loop will block the thread, … Read more
I used to wonder a lot about the same! A GUI main loop looks like this, in pseudo-code: void App::exec() { for(;;) { vector<Waitable> waitables; waitables.push_back(m_networkSocket); waitables.push_back(m_xConnection); waitables.push_back(m_globalTimer); Waitable* whatHappened = System::waitOnAll(waitables); switch(whatHappened) { case &m_networkSocket: readAndDispatchNetworkEvent(); break; case &m_xConnection: readAndDispatchGuiEvent(); break; case &m_globalTimer: readAndDispatchTimerEvent(); break; } } } What is a “Waitable”? Well, it’s … Read more
The standard approach is to use the select module. However, this doesn’t work on Windows. For that, you can use the msvcrt module’s keyboard polling. Often, this is done with multiple threads — one per device being “watched” plus the background processes that might need to be interrupted by the device.
Asynchronous Asynchronous literally means not synchronous. Email is asynchronous. You send a mail, you don’t expect to get a response NOW. But it is not non-blocking. Essentially what it means is an architecture where “components” send messages to each other without expecting a response immediately. HTTP requests are synchronous. Send a request and get a … Read more
The biggest advantage of nonblocking or asynchronous I/O is that your thread can continue its work in parallel. Of course you can achieve this also using an additional thread. As you stated for best overall (system) performance I guess it would be better to use asynchronous I/O and not multiple threads (so reducing thread switching). … Read more
I have the choice in between either having a bunch of mutexes or a single one for an object. If you have many threads and the access to the object happens often, then multiple locks would increase parallelism. At the cost of maintainability, since more locking means more debugging of the locking. How efficient is … Read more
In many circumstances they are different names for the same thing, but in some contexts they are quite different. So it depends. Terminology is not applied in a totally consistent way across the whole software industry. For example in the classic sockets API, a non-blocking socket is one that simply returns immediately with a special … Read more