![]() ![]() NET 4.0 should have a whole bunch of properly implemented thread-safe collections, but that's still nearly a year away unfortunately. This function is an extension to the standard. To avoid errors when threads use MSMPIWaitsomeinterruptible in multi-threaded applications, all threads must acquire the global lock before they call MPI functions. So as you can't safely dequeue anything from a synchronized queue, I wouldn't bother with it and would just use manual locking. Applications should normally allocate the queue structure on the stack each time they acquire the lock. checking the count and dequeueing the item) as follows: object item You can safely write this using a manual lock around the entire unit-of-work (i.e. the next line will throw an InvalidOperationException. at this point another thread dequeues the last item, and then This occurs because each individual operation is thread-safe, but the value of Count can change between when you query it and when you use the value. There's a classic race condition with a synchronized queue, shown below where you check the Count to see if it is safe to dequeue, but then the Dequeue method throws an exception indicating the queue is empty. There's a major problem with the Synchronized methods in the old collection library, in that they synchronize at too low a level of granularity (per method rather than per unit-of-work). If calling Synchronized() doesn't ensure thread-safety what's the point of it? Am I missing something here? ![]() Or is it recommended to use Queue.Synchronized like this: Queue.Synchronized(myQueue).whatever_i_want_to_do() įrom reading the MSDN docs it says I should use Queue.Synchronized to make it thread-safe, but then it gives an example using a lock object. Would it be better to use a lock object like this: lock(myLockObject) Wouldn’t want to do it in our 41 foot sailboat.I have a Queue object that I need to ensure is thread-safe. Requiring a Plan B.Īt this time the lock is being repaired. Only option for passing thru is during night hours along with heavily backed up barge traffic. Working seven days a week, day light to dark. Called lockmaster to check status of repairs. Pay close attention to depths- we went aground while making circles but fortunately were able to get ourselves free.Īrrived at Lake Charles headed east. He even called us several times with additional instructions while we waited. Although we had to turn circles for a while, he put us at the front of the que. Called lockmaster by phone and he was very helpful. Went through eastbound on morning of 4 Dec 19. See my note on the Black Bayou Pontoon bridge.Įd Note: Daily closures due to maintenance. Went through slack (no doors) when opened. We went to the front of the line and waited until we got the call. That was a good thing as there were over 30 barges lined up waiting as we passed them westbound. We contacted the lock the day before and they told us they would lock pleasure craft through before they started the barges that were lined up for the 5PM opening. Sam of WhatYachtToDo on a training and delivery journey. The lock is closed Monday through Friday from 7am to 5pm - lock master advised it would be open for us (pleasure boaters who prefer not to transit in darkness) Saturday/Sundayįebruary 15, 2022. Ive tried implementing the above structures and wonder about their safety and performance. In a project Im currently working on, I need the implementation of ThreadPool along with a thread-safe queue. View location on the Waterway Guide Explorer Topic: C++ Implementation of Lock-Free Queue and ThreadPool classes. They recommend calling them when you reach the devils elbow and they will give you further instructions. URL links are allowed only if they inform the content – no “advertising” your business or blog.Comments must be understandable and clear enough to inform other boaters.Comments must describe commenter's personal experience – “hearsay” reports will be rejected.Comments containing personal attacks will be rejected or returned for resubmission. ![]()
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