Classical Synchronization Problems • Producer-Consumer ProblemEasy⏱️ ~2 min
What is the Producer-Consumer Problem?
Problem Statement
Producer-Consumer: Some threads create items (producers) and add them to a shared buffer. Other threads remove items (consumers) and process them. We must ensure exclusive access to the buffer and coordinate when it is empty or full.
Producer-Consumer Pattern
The Two Constraints
1. Mutual exclusion: Only one thread can modify the buffer at a time. Otherwise, two producers might put items in the same slot, or a producer and consumer might corrupt each other.
2. Condition synchronization: Consumers must wait when the buffer is empty. If there are no items, there is nothing to consume. They should not busy-wait.
Think Of It Like A Warehouse
Delivery trucks (producers) bring packages. Workers (consumers) load packages onto outgoing trucks. Only one person can access a shelf at a time. If shelves are empty, workers wait for deliveries instead of wandering around.
Key Point: Producer-consumer is the canonical coordination problem. Master it and you understand thread coordination.
💡 Key Takeaways
✓Producers create items and add to shared buffer. Consumers remove and process items.
✓Buffer access must be mutually exclusive. Two threads cannot add/remove simultaneously.
✓Consumer blocks on empty buffer. Must wait until producer adds an item.
✓Bounded buffer adds constraint: producer blocks when buffer is full.
✓This pattern is ubiquitous: message queues, event handling, logging, pipelines.
📌 Examples
1Event handling: mouse/keyboard events go into buffer, event handler threads process them.
2Logging: application threads produce log entries, logging thread writes them to disk.