Performance

Prism provides comprehensive performance features for fast test execution and performance analysis.

Parallel Execution

Run tests across multiple worker processes:

vendor/bin/prism test --parallel 4

Or use the short flag:

vendor/bin/prism test -j 4

How It Works

1. Test files divided into batches
2. Each batch runs in separate PHP process
3. Results collected and merged
4. Total execution time significantly reduced

Optimal Worker Count

# Use CPU core count
vendor/bin/prism test -j $(nproc)

# Conservative (50% of cores)
vendor/bin/prism test -j $(($(nproc) / 2))

# Maximum performance
vendor/bin/prism test -j $(nproc --all)

Performance Comparison

# Sequential execution
vendor/bin/prism test
# Time: 45.2s

# Parallel with 4 workers
vendor/bin/prism test -j 4
# Time: 12.8s (3.5x faster)

# Parallel with 8 workers
vendor/bin/prism test -j 8
# Time: 7.1s (6.4x faster)

Performance Profiling

Identify slowest tests with performance profiling:

vendor/bin/prism test --profile

Profile Output

Test Performance Profile

Slowest Tests:
  1. complex-nested-validation (2.145s)
  2. large-array-validation (1.832s)
  3. recursive-schema-test (1.456s)
  4. deep-object-validation (0.987s)
  5. pattern-matching-test (0.654s)

Total Tests: 1,247
Average Duration: 0.023s
Median Duration: 0.012s

Use Cases

• Identify bottlenecks: Find slow tests to optimize
• Monitor performance: Track test suite speed over time
• CI optimization: Prioritize fast tests in pipelines

Baseline Benchmarks

Save and compare performance baselines:

Save Baseline

vendor/bin/prism test --baseline

Save with custom name:

vendor/bin/prism test --baseline "pre-optimization"

Compare Against Baseline

vendor/bin/prism test --compare

Compare against named baseline:

vendor/bin/prism test --compare "pre-optimization"

Benchmark Output

Benchmark Comparison: default

Performance Changes:
  Total Duration: 45.2s → 38.7s (14.4% faster)
  Average Test: 0.036s → 0.031s (13.9% faster)

Significant Changes:
  ✓ complex-validation: 2.145s → 1.234s (42.5% faster)
  ✓ array-processing: 1.832s → 1.123s (38.7% faster)
  ✗ string-validation: 0.234s → 0.387s (65.4% slower)

Tests Analyzed: 1,247
Improved: 892 (71.5%)
Degraded: 123 (9.9%)
Unchanged: 232 (18.6%)

Workflow Example

# Save baseline before optimization
vendor/bin/prism test --baseline "before-cache"

# Make optimizations to validator
vim src/Validator.php

# Compare performance
vendor/bin/prism test --compare "before-cache"

Incremental Testing

Run only changed tests for fast iteration:

vendor/bin/prism test --incremental

How It Works

1. Tracks file modification times
2. Identifies changed test files
3. Only runs tests from changed files
4. Significantly faster during development

Example Workflow

# First run - all tests execute
vendor/bin/prism test --incremental
# Time: 45.2s

# Make small change to one test file
vim tests/validation/strings.json

# Only changed file tests run
vendor/bin/prism test --incremental
# Time: 0.8s (56x faster)

Cache Management

Cache stored in .prism/incremental-cache.json:

{
  "tests/validation/strings.json": 1703001234,
  "tests/validation/numbers.json": 1703001156,
  "tests/validation/objects.json": 1703000987
}

Clear cache to force full run:

rm .prism/incremental-cache.json

Combining Performance Features

Maximize performance by combining features:

Development Workflow

Fast iteration with incremental mode and watch:

vendor/bin/prism test --incremental --watch

CI Optimization

Parallel execution with profiling:

vendor/bin/prism test -j 8 --profile

Performance Monitoring

Baseline comparison with profiling:

vendor/bin/prism test --compare "main" --profile

Watch Mode

Automatically re-run tests when files change:

vendor/bin/prism test --watch

How It Works

1. Runs initial test suite
2. Monitors test files for changes
3. Automatically re-runs tests on change
4. Continues until interrupted (Ctrl+C)

Watch Output

[12:34:56] Initial run completed (45.2s)
[12:35:12] Watching for changes...
[12:36:08] Change detected in tests/validation/strings.json
[12:36:08] Re-running tests...
[12:36:09] Tests completed (0.8s)
[12:36:09] Watching for changes...

Best Practices

Combine watch mode with other features:

# Watch with incremental testing
vendor/bin/prism test --watch --incremental

# Watch with specific filter
vendor/bin/prism test --watch --filter "string"

# Watch with failures only
vendor/bin/prism test --watch --failures

Performance Best Practices

1. Use Parallel Execution in CI

.github/workflows/tests.yml

- name: Run Tests
  run: vendor/bin/prism test -j ${{ steps.cpu.outputs.count }}

2. Profile Regularly

Monitor test suite performance:

# Weekly baseline
vendor/bin/prism test --baseline "$(date +%Y-%m-%d)"

# Compare against last week
vendor/bin/prism test --compare "$(date -d '7 days ago' +%Y-%m-%d)"

3. Optimize Slow Tests

Use profiling to identify and optimize:

vendor/bin/prism test --profile | grep -A 10 "Slowest Tests"

4. Incremental During Development

Always use incremental mode when developing:

alias prism-dev="vendor/bin/prism test --incremental --watch"

5. Filter Before Profiling

Profile specific test subsets:

vendor/bin/prism test --filter "validation" --profile

Performance Metrics

Execution Time

Total time from start to finish:

vendor/bin/prism test
# Total execution time: 45.234s

Test Duration

Individual test execution times:

vendor/bin/prism test --profile
# Shows per-test durations

Throughput

Tests executed per second:

# 1,247 tests in 45.2s = 27.6 tests/second

Next Steps

• Learn about advanced features
• Explore output formats
• See custom assertions