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Multithreading in Java
Multithreading in Java
Producer-Consumer
Great job! You've come a long way, and we've explored plenty of theory and practical examples!
You might have encountered the Producer-Consumer
pattern in other sections, but you might not have realized it. In this section, we will discuss it in detail, and if anything from the previous examples was unclear, it will become clear in this section!
The Producer-Consumer
pattern involves two types of threads, which are clear from the name: Producer and Consumer.
The Producer
will produce some data that it will put into a shared buffer/queue to which the Consumer
also has access, and it will just consume this data from the data store location.
Note
The main goal of the pattern is to separate the production and consumption of data, allowing producers to function independently of consumers.
Where It is Used
This pattern is commonly employed in systems where asynchronous data processing is required. We will explore what asynchrony
means in detail later.
In practice, this pattern is frequently used for event processing systems, data logging, network request handling, and parallel data processing.
Imagine a conveyor belt in a factory where one worker places parts onto the conveyor belt (producer), and another worker removes and assembles them into a product (consumer). The producer and consumer might operate at different speeds, but the conveyor (buffer) helps them stay in sync.
What Does it Look Like in Code?
Let's consider an example of using BlockingQueue
to implement the Producer-Consumer
pattern.
Note
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ExampleProducerConsumer
Consumer
Producer
public class ExampleProducerConsumer { public static void main(String[] args) { BlockingQueue<Integer> queue = new LinkedBlockingQueue<>(); // Shared queue Thread producerThread = new Thread(new Producer(queue)); Thread consumerThread = new Thread(new Consumer(queue)); producerThread.start(); // Start producer thread consumerThread.start(); // Start consumer thread } }
This program showcases the Producer-Consumer
pattern by utilizing BlockingQueue
to ensure safe interactions between threads.
A BlockingQueue
is established to act as a shared buffer for the Producer
and Consumer
threads.
The Producer
class generates numbers from 0 to 9 and adds them to the queue, and then places a signaling value of -1 to indicate that production is finished.
The Consumer
class repeatedly retrieves numbers from the queue. When it encounters the -1 signaling value, it ceases to consume.
In the main method, the shared queue is initialized, and the producer and consumer threads are created and started. The Producer
adds items to the queue while the Consumer
processes these items.
Why It is Used?
The Producer-Consumer
pattern is used to accomplish several goals:
- Thread synchronization: Allows threads to exchange data in a secure manner;
- Performance Improvement: Producers and consumers can work in parallel without blocking each other;
- Buffering: Buffer helps to balance differences in production and consumption speeds.
Note
The
Producer-Consumer
pattern helps to organize safe and efficient interaction between threads in multithreaded programming. It allows producers and consumers to work independently using a buffer for synchronization, which improves performance and prevents blocking.
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