1/13/2024 0 Comments Priority queueThe patient with the highest priority is checked up first. In a hospital, the emergency room assigns priority numbers to patients. Urgent work is assigned the highest priority and is done first.Ģ. Works are added in random order but each work has a priority. A typical example of a priority queue is work schedule. Realtime Examples of PriorityQueue in Javaġ. Let’s understand it with realtime examples. PriorityQueue was added in Java 1.5 version and it is part of the Java Collection Framework. When accessing elements, the element with the highest priority is removed first before the element with lower priority. In FIFO, elements are added to the end of the queue and removed from the beginning.īut, In Java PriorityQueue, elements are stored in order of their priority. It is an abstract data type similar to an ordinary queue except for its removal algorithm.Īn ordinary queue is a first-in-first-out (FIFO) data structure. Just…some of them will be processed faster :). This would guarantee that each message will always be processed, regardless it’s priority. High-priority queues get more consumers and/or more powerful machines. Using our first example, we would have one queue for paying customers and another one for the non-paying ones. So how do you implement this if you’re on the first two? Simple: you add more buckets! If they get processed at all.Īlso, if we want to talk about specific technologies, both Kafka and Azure Service Bus don’t have support for Priority Queues, only RabbitMQ has it. And this also leads us to its biggest weakness: what if we have a burst of high-priority messages? The low priority ones will always be dragged down to the end of the queue, and will potentially be processed after a lot of time. This approach will guarantee that no matter when a message is enqueued, it’ll always be processed based on its priority, not the insertion time. Think of it like some kind of Min/Max Heap, basically. Higher priority messages will automatically bubble up to the top and being consumed first. A clean and somewhat easy solution is to use a Message Queue that allows setting a priority on each entry. work is likely to be performed on a background worker we have different services with different priorities So let’s see what are our requirements here: But what if we want a unified solution? (Yep I know, probably I stretched this one a little, but bear with me) One quick solution would be to have our client invoking the import API directly when it’s a manual import, and send the Excel file to a queue in the other case. We don’t want to write the import API twice, so we design it so that it accepts multiple rows at the same time, making it suited for bulk import immediately. Bulk insert would be of course slower, we can process it on the background and send a notification to the user later on. Now, manual insert would result in an immediate result. Maybe it’s a data import: they can either insert all the data manually or decide to import an Excel sheet with thousands of records. On the client, users can decide to execute operations singularly or in bulk. Or here’s another example: your system has a backend API and a front-end. So we want these to have a far better experience on our system than all the other freeloaders. Now, being the greedy software engineers we are, we of course love all our customers, but a little bit more the paying ones. You have (hopefully) paying and non-paying customers. Suppose you are designing an application with a freemium model. The name is not exactly saying much so let me give you some example scenarios first. Today I’d like to talk about a very interesting design pattern: Priority Queues.
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