#Delphi xe10 thread safe queue code#

It does not reflect any updates to the collection after GetEnumerator was called. The enumeration represents a moment-in-time snapshot of the contents of the queue. Perhaps something along the lines of, copying the queue to another queue, working on that one, then dequeueing the alarms that were dealt with from the original queue?Д®dit: just been informed of concurrent queue, will check this out now 4 Answers 4 thread safe? So that i wonвЂ™t run into these issues. So my question is, how do i make this more.

#Delphi xe10 thread safe queue code#

HereвЂ™s a bit of code to show my queue, just assume that alarms are being constantly inserted into it However, the problem iвЂ™m running into is that, if an alarm is added to the queue whilst itвЂ™s being traversed, it throws an error to say that the queue has changed whilst you were using it. At an interval, the queue is checked, and for each Alarm in the queue, it fires a method. IsSynchronized always returns false and SyncRoot is always null ( Nothing in Visual Basic).ДЄs a signal from certain devices triggers, an object of type Alarm is added to a queue. Instead, they rely on Interlocked operations to achieve thread-safety.Д«ecause the concurrent collections classes support ICollection, they provide implementations for the IsSynchronized and SyncRoot properties, even though these properties are irrelevant. The ConcurrentQueue and ConcurrentStack classes do not use locks at all. For collection classes that use spinning, this efficiency means that multiple threads can add and remove items at a very high rate. When wait times are expected to be very short, spinning is far less computationally expensive than waiting, which involves an expensive kernel transition. These synchronization types typically use busy spinning for brief periods before they put the thread into a true Wait state. Some of the concurrent collection types use lightweight synchronization mechanisms such as SpinLock, SpinWait, SemaphoreSlim, and CountdownEvent, which are new in the. Fine-Grained Locking and Lock-Free Mechanisms NET Framework 2.0 collection classes, but also more efficient and more complete thread safety than the. NET Framework 4 because they provide not only the type safety of the.

We recommend the concurrent collections classes in the. NET Framework 2.0 collection classes do not provide any thread synchronization user code must provide all synchronization when items are added or removed on multiple threads concurrently. These classes provide improved type safety and performance compared to the. These include List, Dictionary, and so on. NET Framework 2.0 are found in the namespace. The collection classes introduced in the. For more information, see Synchronization in Generic Collections. Also, the design is not completely protected from race conditions. This is not scalable and can cause significant performance degradation for large collections. Therefore, each thread that is attempting to access the collection must wait for its turn to take the one lock. The wrapper works by locking the entire collection on every add or remove operation. These collections, which include the commonly used ArrayList and Hashtable, provide some thread-safety through the Synchronized property, which returns a thread-safe wrapper around the collection. NET Framework 1.0 are found in the System.Collections namespace. Fine-Grained Locking and Lock-Free Mechanisms.