workload-balancing

Workload Balancing Skill

Distribute work efficiently across parallel workers to maximize throughput and minimize completion time.

Workflow

1. Characterize the workload (uniform vs. variable task times)
2. Identify bottlenecks (stragglers, uneven distribution)
3. Select balancing strategy based on workload characteristics
4. Implement partitioning and scheduling logic
5. Monitor and adapt to runtime conditions

Load Balancing Decision Tree

What's the workload characteristic?

Uniform task times:
├── Known count → Static partitioning (equal chunks)
├── Streaming input → Round-robin distribution
└── Large items → Size-aware partitioning

Variable task times:
├── Predictable variance → Weighted distribution
├── Unpredictable → Dynamic scheduling / work stealing
└── Long-tail distribution → Work stealing + time limits

Resource constraints:
├── Memory-bound workers → Memory-aware assignment
├── Heterogeneous workers → Capability-based routing
└── Network costs → Locality-aware placement

Balancing Strategies

Strategy 1: Static Chunking (Uniform Workloads)

Best for: predictable, similar-sized tasks

from concurrent.futures import ProcessPoolExecutor
import numpy as np

def static_balanced_process(items, num_workers=4):
    """Divide work into equal chunks upfront."""
    chunks = np.array_split(items, num_workers)

    with ProcessPoolExecutor(max_workers=num_workers) as executor:
        results = list(executor.map(process_chunk, chunks))

    return [item for chunk_result in results for item in chunk_result]

Strategy 2: Dynamic Task Queue (Variable Workloads)

Best for: unpredictable task durations

from concurrent.futures import ProcessPoolExecutor, as_completed
from queue import Queue

def dynamic_balanced_process(items, num_workers=4):
    """Workers pull tasks dynamically as they complete."""
    results = []

    with ProcessPoolExecutor(max_workers=num_workers) as executor:
        # Submit one task per worker initially
        futures = {executor.submit(process_item, item): item
                   for item in items[:num_workers]}
        pending = list(items[num_workers:])

        while futures:
            done, _ = wait(futures, return_when=FIRST_COMPLETED)

            for future in done:
                results.append(future.result())
                del futures[future]

                # Submit next task if available
                if pending:
                    next_item = pending.pop(0)
                    futures[executor.submit(process_item, next_item)] = next_item

    return results