02. Dart Concurrency: Event Loops, Microtask Queue, Futures, Streams & Isolates (Spawn/Compute) • Flutter & Dart Mobile Systems Architecture • Rishabh Ki Kaksha

Flutter & Dart Mobile Systems Architecture › 02. Dart Concurrency: Event Loops, Microtask Queue, Futures, Streams & Isolates (Spawn/Compute)

45 mins

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Course Syllabus

Module 1: Dart 3+ Language Internals, Sound Null Safety & Concurrency (Isolates)

01. Dart 3+ Evolution: Sound Null Safety, Records, Pattern Matching & Sealed Classes 02. Dart Concurrency: Event Loops, Microtask Queue, Futures, Streams & Isolates (Spawn/Compute) 03. Dart Memory Management: Generational Garbage Collection & Object Pool Allocation

Part 1: Dart Mastery & Widget Tree Engine

Module 2: Flutter Rendering Pipeline: 3 Trees Architecture & Impeller Engine

04. Flutter Rendering Architecture: The 3 Trees (Widget Tree, Element Tree & RenderObject Tree) 05. The Impeller Rendering Engine: Vulkan/Metal Pre-compiled Shaders & Zero Junk Architecture 06. Custom RenderObjects & CustomPainter: Building High-Performance 60FPS Charts & UI Effects

Part 2: Platform Channels, Canvas & App Deployment

Module 3: Advanced State Management: Bloc, Cubit, Riverpod 2 & Signals

07. State Management Overview: Ephemeral vs App State & InheritedWidget Internals 08. BLoC (Business Logic Component) & Cubit Architecture with Reactive Streams 09. Riverpod 2.0 Masterclass: Auto-Dispose, Family Providers & Code Generation (riverpod_generator)

Module 4: Declarative Routing, Deep Linking with GoRouter & Micro-Apps

10. Declarative Navigation with GoRouter: URL-based Routing, Nested ShellRoutes & Redirect Guards 11. Deep Linking Architecture on Android & iOS with GoRouter Integration 12. Micro-App Architecture & Modularization in Enterprise Flutter Codebases

Module 5: Native Platform Channels, FFI (Foreign Function Interface) & SQLite (Drift)

13. Platform Channels: MethodChannel, EventChannel & BasicMessageChannel for Swift/Kotlin Interop 14. Dart FFI (Foreign Function Interface): Calling High-Performance C/C++ & Rust Native Libraries 15. High-Speed Local Persistence: Hive, Isar & Type-Safe SQLite with Drift (Moor)

Module 6: Flutter Clean Architecture, Testing & Multi-Platform Deployment (iOS, Android, Web)

16. Enterprise Clean Architecture: Domain, Data & Presentation Layers Separation 17. Network Resilience Layer: Dio Interceptors, Refresh Token Auto-Retry & Offline Cache Interceptor 18. Comprehensive Testing Suite: Unit Tests, Widget Tests & Integration Tests with Mockito/Mocktail 19. Flutter Web & Desktop Optimization: Responsive Layouts, Wasm Compilation & SEO Strategies 20. Automated CI/CD Pipelines with GitHub Actions, Fastlane & Codemagic for App Store Distribution

Interactive Lesson Studio

# 02. Dart Concurrency: Event Loops, Microtask Queue, Futures, Streams & Isolates (Spawn/Compute)

> Flutter & Dart Notes by Rishabh - Topic 02

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### 1. The Dart Single-Threaded Event Loop Model 🧵

Dart code single isolate thread me run hota hai with 2 internal queues:
1. **Microtask Queue (Highest Priority):** Short internal sync tasks (`scheduleMicrotask`).
2. **Event Queue (Standard):** I/O, Timers, UI Taps, Futures (`Future.delayed`).

```
[ Microtask Queue (Runs until 100% EMPTY) ] ➔ [ Event Queue (Processes 1 Event) ] ➔ Repeat
```

---

### 2. Heavy CPU Offloading with Isolates (`Isolate.run` / `compute`) ⚡

Agar 50MB JSON parse karna ho ya Image filter lagana ho — main UI thread par karne se Flutter UI frame freeze ho jayega.  
**Isolate:** Separate CPU thread with **100% Isolated Memory Space** (No shared memory race conditions!):

```dart
import 'dart:isolate';
import 'dart:convert';

// Heavy CPU work executed in background Isolate:
Future<List<Course>> parseGiganticJson(String rawJson) async {
    return await Isolate.run(() {
        final List dynamicList = jsonDecode(rawJson);
        return dynamicList.map((e) => Course.fromJson(e)).toList();
    });
}
```

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### 3. Master Comparison Matrix

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### 4. Interview Ke 3 Sawal Is Topic Se

1. **Dart Isolates standard OS Threads se alag kyu hain?** -> Standard threads shared memory access karte hain (Mutex/Deadlock risk); Dart Isolates zero shared memory maintain karte hain aur sirf message passing (`SendPort`/`ReceivePort`) se communicate karte hain.
2. **`scheduleMicrotask()` ka misuse UI par kya effect daalta hai?** -> Agar microtask loop me microtasks schedule hote rahein, toh Event Queue starve ho jayegi aur UI completely freeze ho jayegi.
3. **`Isolate.spawn()` aur `Isolate.run()` me kya difference hai?** -> `Isolate.run()` modern short-lived task runner hai jo computation ke baad automatically worker isolate kill karke memory cleanup kar deta hai.

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**Next Topic:** 03. Dart Memory Management: Generational Garbage Collection & Object Pool Allocation

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Rishabh Gehlot

PHP 8+ & Laravel 11 Master Track