multitasking

问题 My app downloads several resources from server, data and data descriptors. These downloads, triggered by user actions, can be performed simultaneously, let's say, up to 50 downloads at a time. All these asynchronous tasks end up creating objects in memory, (e.g. appending leaves to data structures, such as adding keys to mutable dictionaries or objects to arrays). My question is: can this cause stability issues? For instance, if several simultaneous tasks try to add keys to the same

问题 Here's the guts of the program using Parallel::ForkManager. It seems to stop at 200 proccesses, sometimes its around 30, depending on the size of the pgsql query that collects URLs to send to Mojo::UserAgent. There seems to be some hard limits somewhere? Is there a better way to write this so that I don't run into those limits? The machine its running on has 16 CPUs and 128GB of memory, so it can certainly run more than 200 proccesses that will die after the Mojo::UserAgent timeout, which is

问题 I am trying to take advantage of iPhone 4 multitasking feature. I want to run app in background and frequently send http request to send/receive data, is it possible? 回答1: Surprisingly, there is actually very little time-slicing going on in the "multi-tasking" iOS 4.x. What goes on instead is really just application suspend / resume. When an application is sent to the background upon the user tapping the home button, it will stop getting execute cycles after a short while (*). (*) There are a

问题 I am trying to take advantage of iPhone 4 multitasking feature. I want to run app in background and frequently send http request to send/receive data, is it possible? 回答1: Surprisingly, there is actually very little time-slicing going on in the "multi-tasking" iOS 4.x. What goes on instead is really just application suspend / resume. When an application is sent to the background upon the user tapping the home button, it will stop getting execute cycles after a short while (*). (*) There are a

问题 Apple's documentation of "App States and Multitasking" (Section "What to Do When Moving to the Background") say for saving when the app goes to background: Save user data and app state information. All unsaved changes should be written to disk when entering the background. This step is necessary because your app might be quietly killed while in the background for any number of reasons. You can perform this operation from a background thread as needed. When I start a dispatched operation e.g.

问题 I have an application wherein when the user taps iPhone's central button, the application is sent to background, but I want it to be closed. I can hand event and close it, but may be there is some configuration setting to deny running in the background? Thank you 回答1: If you want your app to terminate when the user presses the home button, set the value of UIApplicationExitsOnSuspend to YES in your app's Info.plist file. If you do this, when the user taps the home button the

问题 This question already has answers here : Closed 6 years ago . Possible Duplicate: Force app to close and run in background I'm creating an radio application in ios. There is a minimize button in my application. So what I want to do is when user press that button the application should be run in the background and the app icon should be displayed in the notification area like normal Android radio app. I want to know is it possible in iOS and how can I do that. Any one can show me an example.

问题 In multitasking systems, some abnormal conditions prevent progress of executing processes or threads. I'll refer to both processes and threads simply as "processes". Two of these conditions are called dead-lock and live-lock. The former refers to processes which are blocking each other, thus preventing either from executing. The latter refers to processes which prevent each other from progressing, but do not actually block the execution. For instance, they might continually cause each other

问题 You all might know that iOS takes a screen shot of your application before throwing it into the background. This is usually for a better User experience like quick animation to bring the app back and so on. I don't want my app screen shot to be stored on the device, but I want the multitasking to still exist. I came out with a solution but I'm not sure if I'm heading in the right direction. So, when the applicationDidEnterBackground is called -- I put in an overlay image that will be captured

问题 What is preemptive multitasking? After googling it I couldn't find an answer can someone help me? 回答1: http://en.wikipedia.org/wiki/Preemption_(computing) Read the Wikipedia article. Think of it this way, it is a way to allow you to run many different programs at once without each program needing to have been written to give up the processor's time - the OS handles it. The idea is that each process is "preempted" at some point. 回答2: Preemptive Multitasking requires two main components: A