Bounded queue

As explained in Software Design for Python Programmers

A queue with a fixed maximum capacity that can become full when it contains that many values.

A bounded queue stores values in order while enforcing a fixed maximum capacity. Producers add values at the tail; consumers remove them from the head. When full, producers wait; when empty, consumers wait. section 16.4 section 16.4.2

In a concurrent producer–consumer design, the queue coordinates these state transitions:

• Acquire a shared condition object before checking whether the queue is full or empty. section 16.4.1
• Wait in a loop when the queue remains full for a producer or empty for a consumer. section 16.4.1
• Notify waiting threads after an insertion makes the queue nonempty or a removal makes it nonfull. section 16.4
• Recheck the condition after waking because another thread may have changed the queue first. section 16.4.1

Two producers and three consumers

A Python example constructs BoundedQueue(8), runs two producers for five turns each, and runs three consumers. Producers enter values, consumers remove them, and a zero sentinel lets consumers terminate after production finishes. section 16.4.2

Figure 16.9 The producer and consumer threads each attempt to acquire queue.condition at the top of its loop. The condition object synchronizes the producer and consumer threads. The producer threads loop to enter values into the shared bounded queue, and the consumer threads loop to remove values from the queue. A producer thread cannot enter a value into the queue when the queue is full. A consumer thread cannot remove a value from an empty queue.

Use the synchronization diagram to trace how producers and consumers acquire the condition, wait, modify the queue, and notify one another. section 16.4.1

How Software Design for Python Programmers covers it

How deep it goes

Defines queue operations and condition-based synchronization, including waiting, reacquisition, rechecking, and notification.

Examples

Uses Python classes, two producers, three consumers, capacity eight, queue-state output, and zero end sentinels.

What it assumes

Assumes basic queues and threads while developing condition-based coordination beyond mutexes and semaphores alone.

What you can do after

Build it from scratch using Python threading conditions to synchronize bounded producer-consumer workflows.

How it connects

Connects producer-consumer problems with threads, condition objects, mutexes, semaphores, and shared resources.

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Also explained in

• 

  liveBookmanning.com
  Python Concurrency with asyncioA bounded queue is a queue configured with a finite maximum capacity for stored items.
• 

  liveBookmanning.com
  Rust in Action: Systems programming concepts and techniquesA bounded queue is a queue with a fixed capacity that can make producers wait when no space is available.

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Related concepts

• queuekind of · A queue is an ordered collection that holds items for retrieval or processing, typically removing them in the order they were added.
• backpressureimplements · Backpressure is a flow-control mechanism in which downstream capacity constraints prompt upstream producers to slow, limit, pause, or reject work or data.
• clientused by · A client is a person, organization, device, or software component that receives or uses a product, service, resource, or functionality provided by another entity.
• producer-consumerused by · The producer-consumer model coordinates components that generate data with components that retrieve and process it, typically through a buffer or queue.
• producerused by · A producer is an entity or process that creates or supplies values, data, messages, events, or work for another entity to consume.

This explainer was generated by Manning's knowledge graph from the text of Software Design for Python Programmers. The section links point to the parts of the book it draws on.