Parallel Investigation

Parallel Investigation

You are coordinating parallel investigation threads to explore multiple hypotheses or approaches simultaneously. This is effective for complex problems where the root cause is unclear.

Core Principle

When uncertain, explore multiple paths in parallel. Converge when evidence points to an answer.

Parallel investigation reduces time-to-solution for complex problems by eliminating serial bottlenecks.

When to Use Parallel Investigation

Use this methodology when:

• Root cause is unknown with multiple plausible theories
• Problem is complex with many interacting components
• Time pressure requires faster resolution
• Multiple team members are available
• Initial investigation hasn't narrowed down the cause

Don't use when:

• Problem is straightforward
• Only one likely cause
• Resources are constrained

Investigation Structure

Phase 1: Problem Decomposition

Break the problem into independent investigation threads:

Problem: API responses are slow

Investigation Threads:
├── Thread A: Database performance
│   └── Check slow queries, indexes, connection pool
├── Thread B: Application code
│   └── Profile endpoint handlers, check for N+1
├── Thread C: Infrastructure
│   └── Check CPU, memory, network latency
└── Thread D: External services
    └── Check third-party API response times

Each thread should be:

• Independent (can be investigated without blocking others)
• Focused (clear scope and success criteria)
• Time-boxed (defined duration before sync)

Phase 2: Thread Assignment

Assign threads with clear ownership:

## Thread A: Database Performance
**Investigator:** [Name/Agent A]
**Duration:** 30 minutes
**Scope:**
- Query execution times
- Index utilization
- Connection pool metrics
**Report Format:** Summary + evidence

## Thread B: Application Code
**Investigator:** [Name/Agent B]
...

Phase 3: Parallel Execution

Each thread follows this pattern:

1. Gather evidence specific to thread scope
2. Document findings as you go
3. Identify if thread is leading to answer or dead end
4. Prepare summary for sync point

Thread Log Template:

## Thread: [Name]
**Start:** [Time]

### Findings
- [Timestamp] [Finding 1]
- [Timestamp] [Finding 2]

### Evidence
- [Screenshot/Log/Metric]

### Preliminary Conclusion
[What this thread suggests about the problem]

Phase 4: Sync Points

Regular convergence to share findings:

Sync Point Agenda:
1. Thread A report (2 min)
2. Thread B report (2 min)
3. Thread C report (2 min)
4. Thread D report (2 min)
5. Discussion & correlation (5 min)
6. Decision: Continue, pivot, or converge (3 min)

Sync Point Decisions:

• Continue: Threads are progressing, continue parallel
• Pivot: Redirect threads based on new evidence
• Converge: One thread found the answer, others join

Phase 5: Convergence

When a thread identifies the likely cause:

1. Validate - Other threads verify the finding
2. Deep dive - Focused investigation on identified cause
3. Document - Compile findings from all threads

Coordination Patterns

Hub and Spoke

One coordinator, multiple investigators:

        ┌─────────┐
        │  Hub    │
        │(Coord)  │
        └────┬────┘
             │
    ┌────────┼────────┐
    ▼        ▼        ▼
┌───────┐┌───────┐┌───────┐
│Thread ││Thread ││Thread │
│   A   ││   B   ││   C   │
└───────┘└───────┘└───────┘

Coordinator responsibilities:

• Assigns threads
• Tracks progress
• Calls sync points
• Makes convergence decisions

Peer Network

Equal investigators sharing findings:

┌───────┐     ┌───────┐
│Thread │◄───▶│Thread │
│   A   │     │   B   │
└───┬───┘     └───┬───┘
    │             │
    ▼             ▼
    ◄─────────────►
         Shared
         Channel

Each investigator:

• Posts findings to shared channel
• Reviews others' findings
• Volunteers to converge when pattern emerges

Communication Protocol

During Investigation

[Thread A] [Status] Starting query analysis
[Thread B] [Finding] No N+1 patterns in user endpoint
[Thread A] [Finding] Slow query: SELECT * FROM orders WHERE...
[Thread C] [Dead End] CPU and memory within normal
[Thread A] [Hot Lead] Missing index on orders.user_id

At Sync Point

## Thread A Summary

**Status:** Hot Lead
**Key Finding:** Missing index on orders.user_id
**Evidence:** Query taking 3.2s, explain shows table scan
**Recommendation:** This is likely the cause, suggest converge

Decision Framework

At each sync point:

Time Management

Hour 1:
├── 0:00 - Problem decomposition
├── 0:10 - Thread assignment
├── 0:15 - Parallel investigation begins
├── 0:45 - Sync point #1
├── 0:50 - Continue/pivot/converge decision

Hour 2 (if needed):
├── 1:00 - Continue investigation
├── 1:30 - Sync point #2
├── 1:35 - Final convergence

Documentation

Final Report Structure

# Investigation: [Problem]

## Summary
[Brief description and resolution]

## Threads Explored

### Thread A: [Area]
- Investigator: [Name]
- Findings: [Summary]
- Outcome: [Lead/Dead End/Root Cause]

### Thread B: [Area]
...

## Root Cause
[Detailed explanation of what was found]

## Evidence
- [Evidence 1]
- [Evidence 2]

## Resolution
[What was done to fix]

## Lessons Learned
- [Learning 1]
- [Learning 2]

Integration with Other Skills

• debugging/root-cause-analysis: Each thread follows RCA principles
• debugging/hypothesis-testing: Threads test specific hypotheses
• handoff-protocols: When passing thread to another person