perf-workshop/scenario7-pyroscope/app.py

#!/usr/bin/env python3
"""
Scenario 7: Continuous Profiling with Pyroscope
===============================================
A simple Flask web app instrumented with Pyroscope for continuous profiling.

SETUP:
1. Start Pyroscope: docker run -p 4040:4040 grafana/pyroscope
2. Install deps: pip install flask pyroscope-io
3. Run this app: python3 app.py
4. Generate load: ./loadgen.sh (or curl in a loop)
5. View profiles: http://localhost:4040

The app has intentionally slow endpoints to demonstrate profiling.
"""

import os
import time
import math
import hashlib
from functools import lru_cache

# Try to import pyroscope, gracefully handle if not installed
try:
    import pyroscope
    PYROSCOPE_AVAILABLE = True
except ImportError:
    PYROSCOPE_AVAILABLE = False
    print("Pyroscope not installed. Run: pip install pyroscope-io")
    print("Continuing without profiling...\n")

from flask import Flask, jsonify

app = Flask(__name__)

# Configure Pyroscope
if PYROSCOPE_AVAILABLE:
    pyroscope.configure(
        application_name="workshop.flask.app",
        server_address="http://localhost:4040",
        # Enable profiling for specific aspects
        tags={
            "env": "workshop",
            "version": "1.0.0",
        }
    )


# ============================================================
# Endpoint 1: CPU-intensive computation
# ============================================================

def compute_primes_slow(n):
    """Intentionally slow prime computation."""
    primes = []
    for num in range(2, n):
        is_prime = True
        for i in range(2, int(math.sqrt(num)) + 1):
            if num % i == 0:
                is_prime = False
                break
        if is_prime:
            primes.append(num)
    return primes


@app.route('/api/primes/<int:n>')
def primes_endpoint(n):
    """CPU-bound endpoint - compute primes up to n."""
    n = min(n, 50000)  # Limit to prevent DoS
    start = time.time()
    primes = compute_primes_slow(n)
    elapsed = time.time() - start
    return jsonify({
        'count': len(primes),
        'limit': n,
        'elapsed_ms': round(elapsed * 1000, 2)
    })


# ============================================================
# Endpoint 2: Repeated expensive computation (needs caching)
# ============================================================

def expensive_hash(data, iterations=1000):
    """Simulate expensive computation."""
    result = data.encode()
    for _ in range(iterations):
        result = hashlib.sha256(result).digest()
    return result.hex()


@app.route('/api/hash/<data>')
def hash_endpoint(data):
    """
    This endpoint recomputes the hash every time.
    Profile will show expensive_hash taking lots of time.
    See hash_cached endpoint for improvement.
    """
    start = time.time()
    result = expensive_hash(data)
    elapsed = time.time() - start
    return jsonify({
        'input': data,
        'hash': result[:16] + '...',
        'elapsed_ms': round(elapsed * 1000, 2)
    })


@lru_cache(maxsize=1000)
def expensive_hash_cached(data, iterations=1000):
    """Cached version of expensive_hash."""
    result = data.encode()
    for _ in range(iterations):
        result = hashlib.sha256(result).digest()
    return result.hex()


@app.route('/api/hash_cached/<data>')
def hash_cached_endpoint(data):
    """Cached version - compare profile with /api/hash."""
    start = time.time()
    result = expensive_hash_cached(data)
    elapsed = time.time() - start
    return jsonify({
        'input': data,
        'hash': result[:16] + '...',
        'elapsed_ms': round(elapsed * 1000, 2),
        'cache_info': str(expensive_hash_cached.cache_info())
    })


# ============================================================
# Endpoint 3: I/O simulation
# ============================================================

@app.route('/api/slow_io')
def slow_io_endpoint():
    """
    Simulate slow I/O (database query, external API, etc.)
    This won't show much in CPU profiles - it's I/O bound!
    """
    time.sleep(0.1)  # Simulate 100ms I/O
    return jsonify({'status': 'ok', 'simulated_io_ms': 100})


# ============================================================
# Endpoint 4: Mix of work types
# ============================================================

@app.route('/api/mixed/<int:n>')
def mixed_endpoint(n):
    """Mixed workload: some CPU, some I/O."""
    n = min(n, 1000)
    
    # CPU work
    total = 0
    for i in range(n * 100):
        total += math.sin(i) * math.cos(i)
    
    # Simulated I/O
    time.sleep(0.01)
    
    # More CPU work
    data = str(total).encode()
    for _ in range(100):
        data = hashlib.md5(data).digest()
    
    return jsonify({
        'n': n,
        'result': data.hex()[:16]
    })


# ============================================================
# Health check
# ============================================================

@app.route('/health')
def health():
    return jsonify({'status': 'healthy', 'pyroscope': PYROSCOPE_AVAILABLE})


@app.route('/')
def index():
    return '''
    <h1>Pyroscope Demo App</h1>
    <h2>Endpoints:</h2>
    <ul>
        <li><a href="/api/primes/10000">/api/primes/&lt;n&gt;</a> - CPU intensive</li>
        <li><a href="/api/hash/hello">/api/hash/&lt;data&gt;</a> - Expensive (uncached)</li>
        <li><a href="/api/hash_cached/hello">/api/hash_cached/&lt;data&gt;</a> - Expensive (cached)</li>
        <li><a href="/api/slow_io">/api/slow_io</a> - I/O simulation</li>
        <li><a href="/api/mixed/100">/api/mixed/&lt;n&gt;</a> - Mixed workload</li>
        <li><a href="/health">/health</a> - Health check</li>
    </ul>
    <h2>Profiling:</h2>
    <p>View profiles at <a href="http://localhost:4040">http://localhost:4040</a></p>
    '''


if __name__ == '__main__':
    print("Starting Flask app on http://localhost:5000")
    print("Pyroscope dashboard: http://localhost:4040")
    print("\nGenerate load with: ./loadgen.sh")
    print("Or: for i in $(seq 100); do curl -s localhost:5000/api/primes/5000 > /dev/null; done")
    app.run(host='0.0.0.0', port=5000, debug=False)