Your implementation is correct. The .NET Framework does not provide a built-in concurrent hashset type, unfortunately. However, there are some workarounds. ConcurrentDictionary (recommended) This first one is to use the class ConcurrentDictionary<TKey, TValue> in the namespace System.Collections.Concurrent. In the case, the value is pointless, so we can use a simple byte (1 byte in memory). … Read more
@GP89 mentioned a good solution. Use a queue to send the writing tasks to a dedicated process that has sole write access to the file. All the other workers have read only access. This will eliminate collisions. Here is an example that uses apply_async, but it will work with map too: import multiprocessing as mp … Read more
The difference between a recursive and non-recursive mutex has to do with ownership. In the case of a recursive mutex, the kernel has to keep track of the thread who actually obtained the mutex the first time around so that it can detect the difference between recursion vs. a different thread that should block instead. … Read more
I did it this way once, I hope it helps: bool createdNew; Mutex m = new Mutex(true, “myApp”, out createdNew); if (!createdNew) { // myApp is already running… MessageBox.Show(“myApp is already running!”, “Multiple Instances”); return; }
When I am having a big heated discussion at work, I use a rubber chicken which I keep in my desk for just such occasions. The person holding the chicken is the only person who is allowed to talk. If you don’t hold the chicken you cannot speak. You can only indicate that you want … Read more
I want to make sure this is out there, because it’s so hard to get right: using System.Runtime.InteropServices; //GuidAttribute using System.Reflection; //Assembly using System.Threading; //Mutex using System.Security.AccessControl; //MutexAccessRule using System.Security.Principal; //SecurityIdentifier static void Main(string[] args) { // get application GUID as defined in AssemblyInfo.cs string appGuid = ((GuidAttribute)Assembly.GetExecutingAssembly(). GetCustomAttributes(typeof(GuidAttribute), false). GetValue(0)).Value.ToString(); // unique id for … Read more
It’s just the way that condition variables are (or were originally) implemented. The mutex is used to protect the condition variable itself. That’s why you need it locked before you do a wait. The wait will “atomically” unlock the mutex, allowing others access to the condition variable (for signalling). Then when the condition variable is … Read more
They are NOT the same thing. They are used for different purposes! While both types of semaphores have a full/empty state and use the same API, their usage is very different. Mutual Exclusion Semaphores Mutual Exclusion semaphores are used to protect shared resources (data structure, file, etc..). A Mutex semaphore is “owned” by the task … Read more
1800 INFORMATION is more or less correct, but there are a few issues I wanted to correct. boost::shared_mutex _access; void reader() { boost::shared_lock< boost::shared_mutex > lock(_access); // do work here, without anyone having exclusive access } void conditional_writer() { boost::upgrade_lock< boost::shared_mutex > lock(_access); // do work here, without anyone having exclusive access if (something) { … Read more
What is the correct way to create a single-instance WPF application?