parallel-execution

Parallel Execution

CRITICAL: This skill teaches how to execute multiple tasks simultaneously for maximum efficiency.

The Fundamental Rule

ALL Task calls MUST be in a SINGLE assistant message for true parallelism.

If Task calls are in separate messages, they run SEQUENTIALLY, not in parallel.

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Why Parallel Execution Matters

Sequential (SLOW - AVOID)

Message 1: Start Task A
           ↓ wait for completion
Message 2: Start Task B
           ↓ wait for completion
Message 3: Start Task C
           ↓ wait for completion

Total time = A + B + C = 90 seconds (if each takes 30s)

Parallel (FAST - USE THIS)

Message 1: Start Task A ─┐
           Start Task B ─┼─ All run simultaneously
           Start Task C ─┘

Total time ≈ max(A, B, C) = 30 seconds

Speedup: 3x faster with 3 parallel tasks

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How to Execute in Parallel

Step 1: Identify Independent Tasks

Tasks are independent when:

• They don't depend on each other's output
• They don't modify the same files
• They can run in any order

Step 2: Launch ALL Tasks in ONE Message

<!-- CORRECT: All tasks in single message = PARALLEL -->
<task>
  <description>Analyze authentication module</description>
  <prompt>Review src/auth for security patterns...</prompt>
</task>

<task>
  <description>Analyze API layer</description>
  <prompt>Review src/api for REST best practices...</prompt>
</task>

<task>
  <description>Analyze database layer</description>
  <prompt>Review src/db for query optimization...</prompt>
</task>

Step 3: Collect and Synthesize Results

After all tasks complete, combine their findings into a unified response.

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Parallelization Patterns

Pattern 1: Task-Based Parallelization

When you have N independent tasks, spawn N subagents:

Implementation Plan:
1. Implement auth module
2. Create API endpoints
3. Add database schema
4. Write unit tests
5. Update documentation

Launch 5 parallel subagents:
├─ Subagent 1: Implement auth module
├─ Subagent 2: Create API endpoints
├─ Subagent 3: Add database schema
├─ Subagent 4: Write unit tests
└─ Subagent 5: Update documentation