Openclaw Skill Parallel Tasks

Execute multiple tasks in parallel with timeout protection, error isolation, and real-time progress feedback. Use when user says "run these in parallel", "parallel execution", "concurrent tasks", or wants multiple independent tasks done simultaneously with proper error handling and timeout control.

Parallel Tasks Skill

Execute multiple tasks in parallel with enterprise-grade reliability: timeout protection, error isolation, and real-time progress feedback.

When to Use

Use this skill when:

• User says "run these in parallel" or "do these simultaneously"
• Multiple independent tasks need to be executed at once
• User wants faster results by running tasks concurrently
• Tasks are slow and user wants to avoid waiting sequentially

Core Concept

Serial vs Parallel:

SERIAL (slow):
Task 1 → Task 2 → Task 3  (5min + 5min + 5min = 15min)

PARALLEL (fast):
Task 1 ─┬─> (5min total, not 15min)
Task 2 ─┼─>
Task 3 ─┘

Usage

Basic Parallel Execution

/parallel
- Task 1: Search for docs
- Task 2: Search for code
- Task 3: Search for examples

Named Tasks with Custom Timeout

/parallel timeout=300
- [search-docs] Search for relevant documentation
- [search-code] Find similar implementations
- [analyze] Analyze the results

CLI Usage (scripts/executor.ts)

# Simple usage
node scripts/executor.ts "Research AI trends" "Research market analysis"

# Named tasks with custom timeout
node scripts/executor.ts --timeout 600 \
  --task "[research] Research AI trends" \
  --task "[implement] Build the feature"

# Read from file (one task per line)
node scripts/executor.ts --tasks-file my-tasks.txt --max-concurrent 3

# Named task formats (all equivalent):
# - [name] description
# - - description (auto-named as task-1, task-2, ...)
# - 1. description

Implementation

Core Execution Pattern

The executor uses a semaphore pattern with configurable concurrency:

// 1. Parse tasks from input
const tasks = parseTaskInput(input)

// 2. Execute tasks with concurrency control
const results: TaskResult[] = []
const executing: Promise<void>[] = []

for (const task of tasks) {
  // Wait if at max concurrency
  if (executing.length >= maxConcurrent) {
    await Promise.race(executing)
  }

  const promise = runTask(task).then(result => {
    results.push(result)
    // Remove from executing list
    const idx = executing.indexOf(promise)
    if (idx > -1) executing.splice(idx, 1)
  })

  executing.push(promise)
}

await Promise.all(executing)

Task Execution via hermes cli

async function executeTaskViaSpawn(
  task: Task,
  timeoutSeconds: number
): Promise<TaskResult> {
  const taskId = `parallel-${Date.now()}-${randomId()}`

  return new Promise((resolve) => {
    const proc = spawn('hermes', [
      'cli', '--',
      'sessions_spawn',
      '--task', `"${task.description}"`,
      '--label', `"${task.name}"`,
      '--timeout', String(timeoutSeconds),
      '--session-id', taskId
    ], { stdio: ['ignore', 'pipe', 'pipe'] })

    // Timeout handling
    const timeoutId = setTimeout(() => {
      proc.kill('SIGTERM')
      resolve({
        name: task.name,
        status: 'timeout',
        duration: Date.now() - startTime,
        error: `Exceeded ${timeoutSeconds}s timeout`
      })
    }, timeoutSeconds * 1000)

    proc.on('close', (code, signal) => {
      clearTimeout(timeoutId)
      if (signal === 'SIGTERM') {
        resolve({ name: task.name, status: 'timeout', ... })
      } else if (code === 0) {
        resolve({ name: task.name, status: 'fulfilled', ... })
      } else {
        resolve({ name: task.name, status: 'rejected', ... })
      }
    })
  })
}

Timeout Protection

Option	Default	Description
timeout	300	Default timeout per task (seconds)
Per-task timeout	-	Override global timeout for specific tasks

Behavior: Task auto-terminates after timeout, other tasks continue.

Error Isolation

Each task runs in complete isolation:

Problem	Serial	Parallel (This Skill)
One task fails	All others stop	Only failed task affected
One task hangs	Blocks entire flow	Others continue normally
One task times out	May cascade	Contained, others finish

Concurrency Control

Option	Default	Description
maxConcurrent	5	Maximum tasks running simultaneously

Pattern: Semaphore-style - starts N tasks, when one completes, starts next.

Progress Feedback

Real-time terminal output with colored status:

🚀 Starting 3 tasks in parallel (max 5 concurrent)...

🔄 [task-1] Starting (timeout: 300s)...
🔄 [task-2] Starting (timeout: 300s)...
🔄 [task-3] Starting (timeout: 300s)...
✅ [1/3] [task-1] Complete (23.5s)
✅ [2/3] [task-2] Complete (45.2s)
⏱️  [3/3] [task-3] Timeout after 300s

Task Input Formats

1. Named Tasks (Recommended)

[research] Research AI trends and write report
[implement] Build the feature
[test] Write comprehensive tests

2. Bullet List

- Search for API documentation
- Find relevant code examples
- Check for existing implementations

3. Numbered List

1. Research authentication patterns
2. Design database schema
3. Implement API endpoints

4. Plain Text (auto-named)

Research AI trends
Build the feature
Write tests

→ Auto-named: task-1, task-2, task-3

Output Format

Success Case

✅ Parallel Execution Complete
   3 tasks: 2 succeeded, 1 failed (45.2s total)

┌─────────────────────┬────────────┬────────────┐
│ Task                │ Status     │ Duration   │
├─────────────────────┼────────────┼────────────┤
│ research            │ ✅ fulfilled│ 23.5s      │
│ implement           │ ✅ fulfilled│ 45.2s      │
│ test                │ ⏱️ timeout  │ 300.0s    │
└─────────────────────┴────────────┴────────────┘

❌ Failed Tasks:
   • test: Exceeded 300s timeout

Exit Codes

Code	Meaning
0	All tasks succeeded
1	Some tasks failed or timed out

Options

CLI Options

Option	Default	Description
--timeout, -to	300	Timeout per task (seconds)
--max-concurrent, -m	5	Max concurrent tasks
--stop-on-error	false	Stop all if one fails
--no-progress	false	Suppress progress output
--tasks-file, -f	-	Read tasks from file
--parse	-	Parse stdin to JSON

Per-Task Options (in task description)

[name] description (timeout=600)

Error Handling

Error Types

Status	Cause	Behavior
fulfilled	Task succeeded	Returns result value
timeout	Exceeded timeout	Task terminated, others continue
rejected	Process error	Error captured, others continue
cancelled	User cancelled	All running tasks terminate
no_reply	No output	Reported as warning

Best Practices

1. Independent tasks first: Tasks should not depend on each other
2. Set reasonable timeouts: Don't set 5min if task should take 30s
3. Use named tasks: Easier to debug when something fails
4. Keep tasks focused: One clear goal per task
5. Mind concurrency: Don't set maxConcurrent higher than system can handle

Examples

Example 1: Research Multiple Topics

node scripts/executor.ts \
  "Research Claude Code best practices" \
  "Find OpenClaw skill examples" \
  "Search for agent design patterns"

Example 2: Named Tasks from File

# tasks.txt:
# [research] Research AI trends
# [implement] Build the feature
# [test] Write tests

node scripts/executor.ts --tasks-file tasks.txt --timeout 600

Example 3: Parallel Implementation

node scripts/executor.ts --timeout 600 \
  --task "[backend] Implement user authentication API" \
  --task "[frontend] Build login form component" \
  --task "[database] Create users table migration"

Example 4: Web Scraping

node scripts/executor.ts \
  --task "[store1] Fetch product data from store1.com" \
  --task "[store2] Fetch product data from store2.com" \
  --task "[store3] Fetch product data from store3.com"

Anti-Patterns

❌ Don't use for dependent tasks:

# WRONG - second task depends on first!
node scripts/executor.ts \
  "Create user account" \
  "Send welcome email"

Use sequential execution instead.

❌ Don't use for very fast tasks:

# WRONG - spawning overhead not worth it
node scripts/executor.ts "Read file A" "Read file B" "Read file C"

The overhead of spawning parallel sessions isn't worth it for sub-second tasks.

Related Skills

• subagents - Background agent spawning
• batch-operations - Bulk file operations
• workflow-orchestrator - Complex multi-step workflows