flutter-handling-concurrency
Offload CPU-intensive tasks to background isolates while keeping Flutter UIs responsive.
- Provides three concurrency patterns:
async/awaitfor I/O-bound work,Isolate.run()for one-off heavy computations, andIsolate.spawn()with message passing for persistent background workers - Includes a decision matrix to choose between async operations and isolates based on task type (I/O vs. CPU-bound) and execution frequency
- Covers three complete workflows with step-by-step task checklists: standard async UI with
FutureBuilder, short-lived isolate offloading, and long-lived bidirectional worker communication - Provides three runnable code examples demonstrating
FutureBuilderpatterns, JSON decoding in isolates, andReceivePort/SendPortmessage passing architecture
Managing Dart Concurrency and Isolates
Contents
Core Concepts
Dart utilizes a single-threaded execution model driven by an Event Loop (comparable to the iOS main loop). By default, all Flutter application code runs on the Main Isolate.
- Asynchronous Operations (
async/await): Use for non-blocking I/O tasks (network requests, file access). The Event Loop continues processing other events while waiting for theFutureto complete. - Isolates: Dart's implementation of lightweight threads. Isolates possess their own isolated memory and do not share state. They communicate exclusively via message passing.
- Main Isolate: The default thread where UI rendering and event handling occur. Blocking this isolate causes UI freezing (jank).
- Worker Isolate: A spawned isolate used to offload CPU-bound tasks (e.g., decoding large JSON blobs) to prevent Main Isolate blockage.
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