synchronization

I have two threads in python (2.7). I start them at the beginning of my program. While they execute, my program reaches the end and exits, killing both of my threads before waiting for resolution. I'm trying to figure out how to wait for both threads to finish before exiting. def connect_cam(ip, execute_lock): try: conn = TelnetConnection.TelnetClient(ip) execute_lock.acquire() ExecuteUpdate(conn, ip) execute_lock.release() except ValueError: pass execute_lock = thread.allocate_lock() thread.start_new_thread(connect_cam, ( headset_ip, execute_lock ) ) thread.start_new_thread(connect_cam, (

I need to populate my map with annotations. Each annotation has corresponding Place resource that is being fetched from remote server. Each Place has associated Category - it is fetched from the server too as a separate resource. Let's assume that to populate a given region I need to fetch 100 places, each belonging to the one of 20 categories (actually there are much more of them). I use AFNetworking to fetch the both of resources. I try to cache both places and categories for offline use, so before the annotations are displayed on map, I write fetched resources to the Core Data tables. Each

It is a follow up question of Shared_ptr and Memory Visibility in c++ and Create object in thread A, use in thread B. Mutex required? . This question is more about memory visibility rather than data race. In Java, I have: ExecutorService executor = Executors.newSingleThreadExecutor(); Integer i = new Integer(5); // no write to i afterwards executor.submit(() -> { System.out.println(i); }); I don't think this is thread-safe. Because there is no need to put value 5 in the main memory, it could stay in the main thread's CPU cache. Since there is no memory barrier, the executor thread is not

I don't quite understand the documentation for InitializeCriticalSectionAndSpinCount: http://msdn.microsoft.com/en-us/library/windows/desktop/ms683476(v=vs.85).aspx It says "You can improve performance significantly by choosing a small spin count ..." However, since waiting on a spinner is faster than waiting for an object, doesn't it make sense to have the SpinCount as high as possible? What am I missing? Thanks. (I am using it inside a C DLL used by a multi-threaded application) Here is the code for the critical section, called constantly by a large number of threads: int g_slots[256] = {0};

I have two threads: 'main' and 'worker', and one global variable bool isQuitRequested that will be used by the main thread to inform worker , when it's time to quit its while loop (something like this: while(isQuitRequested == false) { ... do some stuff ... } ) Now, I'm a bit concerned... Do I need to use some kind of mutex protection for isQuitRequested , considering that only one thread ( main ) performs isQuitRequested = true operation, and the other ( worker ) just performs checking and nothing else? I have read What could happen if two threads access the same bool variable at the same

Under what circumstances should each of the following synchronization objects be used? ReaderWriter lock Semaphore Mutex Since wait() will return once for each time post() is called, semaphores are a basic producer-consumer model - the simplest form of inter-thread message except maybe signals. They are used so one thread can tell another thread that something has happened that it's interested in (and how many times), and for managing access to resources which can have at most a fixed finite number of users. They offer ordering guarantees needed for multi-threaded code. Mutexes do what they