semaphore

I have in an HTML page, an element that appears several times, and running the same JS. Problem is, I want it to do a specific function only if it was the first one to run it (his siblings never ran it - YET). I need semaphore to sync between them. I am unable to know how to declare a variable and to do semaphore in this way in JS. There are lots of approaches. You need to put a flag somewhere . In the absence of anything else, you can put it on window , but use a name that's unlikely to conflict with anything else. Then the JavaScript is quite straightforward: if (!window.myUniqueNameFlag) {

I am trying to implement a simple routine using semaphores that will allow me to run only 3 instances of the application. I could use 3 mutexes but that is not a nice approach i tried this so far var hSem:THandle; begin hSem := CreateSemaphore(nil,3,3,'MySemp3'); if hSem = 0 then begin ShowMessage('Application can be run only 3 times at once'); Halt(1); end; How can i do this properly ? Always make sure that you release a semaphore because this is not done automatically if your application dies. program Project72; {$APPTYPE CONSOLE} uses Windows, SysUtils; var hSem: THandle; begin try hSem :=

Since the latest Parse release (v1.6.3) my app gets stuck at launch, and the last breakpoint it hits is [PFFacebookUtils initializeFacebook]; If I hit pause and look at the debugger, the stack trace looks like this: I'm calling [PFFacebookUtils initializeFacebook] in - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions as advised. From googling the semaphore_wait_trap issue, it seems to be related to clashing background threads(?) in Core Data. But I've tried commenting out all my background Parse queries and it still occurs. I tried

I'm working on an implementation of the "Fair Barbershop" problem in Ruby. This is for a class assignment, but I'm not looking for any handouts. I've been searching like crazy, but I cannot seem to find a Ruby implementation of Semaphores that mirror those found in C. I know there is Mutex, and that's great. Single implementation, does exactly what that kind of semaphore should do. Then there's Condition Variables. I thought that this was going to work out great, but looking at these, they require a Mutex for every wait call, which looks to me like I can't put numerical values to the semaphore

I have read the docs for SemaphoreSlim SemaphoreSlim MSDN which indicates that the SemaphoreSlim will limit a section of code to be run by only 1 thread at a time if you configure it as: SemaphoreSlim _semaphoreSlim = new SemaphoreSlim(1, 1); However, it doesn't indicate if it stops the same thread from accessing that code. This comes up with async and await. If one uses await in a method, control leaves that method and returns when whatever task or thread has completed. In my example, I use a button with an async button handler. It calls another method (Function1) with 'await'. Function1 in

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: When should one use a semaphore and when should one use a conditional variable (CondVar) ? 回答1: Locks are used for mutual exclusion. When you want to ensure that a piece of code is atomic, put a lock around it. You could theoretically use a binary semaphore to do this, but that's a special case. Semaphores and condition variables build on top of the mutual exclusion provide by locks and are used for providing synchronized access to shared resources. They can be used for similar purposes. A condition variable is generally used to avoid busy

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: The Sleeping Barber Problem is a classical synchronization problem that many of you may be familiar with or at least heard of. It's based on the premise that a barber (a thread) sleeps when there are no customers (each customer is a thread) in the waiting room (which is a semaphore) . If there is someone, he cuts his hair (symbolizing some processing) and the costumer leaves. If, then, there is no one in the waiting room, the barber goes to sleep. When another customer arrives, he then must wake up the barber. I have made a implementation of

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I want limit resource access in children processes. For example - limit http downloads , disk io , etc.. How can I achieve it expanding this basic code? Please share some basic code examples. pool = multiprocessing . Pool ( multiprocessing . cpu_count ()) while job_queue . is_jobs_for_processing (): for job in job_queue . pull_jobs_for_processing : pool . apply_async ( do_job , callback = callback ) pool . close () pool . join () 回答1: Use the initializer and initargs arguments when creating a pool so as to define a global in all