perf: benchmarks, allocation budgets, and instrumentation

[mhenrixon]

Summary

• Instrumentation: ActiveSupport::Notifications events on Client (send_message, send_batch, read_message, read_batch), Executor (execute), and Serializer (serialize, deserialize) for runtime observability
• Benchmark suite: benchmark-ips + memory_profiler scripts measuring throughput and memory for serialization, client ops, and executor cycles — PGMQ mocked to isolate gem overhead
• Allocation budget specs: CI guardrails that fail if object allocations spike above thresholds or if any objects are retained (leak detection)
• Rake tasks: rake bench, rake bench:serialization, rake bench:client, rake bench:executor, rake bench:memory

Test plan

• All 275 existing specs pass (no regressions from instrumentation changes)
• 5 new allocation budget specs pass
• Rubocop clean on all changed files
• Run bundle exec rake bench to verify benchmark scripts execute end-to-end
• Run bundle exec rake bench:memory to baseline current allocation profile

Summary by CodeRabbit

• New Features

  • Added runtime instrumentation to key client, executor, and serializer operations for performance monitoring.

• Tests

  • Added memory allocation budget tests and leak-detection specs.

• Chores

  • Added benchmarking scripts and Rake tasks to run performance/memory benchmarks.
  • Added profiling dependencies for benchmarking and memory analysis.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 8ab8eea1-386c-400a-9ba4-5a09495274c3

📥 Commits

Reviewing files that changed from the base of the PR and between e90434c and 6a709be.

📒 Files selected for processing (1)

• benchmarks/memory_profile.rb

🚧 Files skipped from review as they are similar to previous changes (1)

• benchmarks/memory_profile.rb

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📝 Walkthrough

Walkthrough

This PR adds benchmarking scripts and Rake tasks, introduces a conditional Instrumentation API, wraps serializer/client/executor hot paths with instrumentation, and adds memory-allocation tests. It also adds test-only gems benchmark-ips and memory_profiler.

Changes

Cohort / File(s)	Summary
Dependency Management Gemfile	Added benchmark-ips (> 2.13) and memory_profiler (> 1.1) to the :test group.
Build Tasks Rakefile	Added bench namespace tasks (serialization, client, executor, memory) plus bench:all and top-level bench.
Benchmarking Helpers benchmarks/bench_helper.rb	New helper module BenchStubs, MockPgmq class, and payload constants for benchmark scripts.
Benchmark Scripts benchmarks/serialization_bench.rb, benchmarks/client_bench.rb, benchmarks/executor_bench.rb, benchmarks/memory_profile.rb	New Benchmark.ips and MemoryProfiler scripts for serialization, client ops, executor execution, and memory profiling.
Instrumentation Layer lib/pgbus/instrumentation.rb	New Pgbus::Instrumentation.instrument(event, payload = {}, &block) that delegates to ActiveSupport::Notifications when available, else yields to the block.
Instrumented Client Operations lib/pgbus/client.rb	Wrapped send_message, send_batch, read_message, and read_batch calls with Instrumentation.instrument emitting pgbus.client.* events and contextual metadata.
Instrumented Executor lib/pgbus/active_job/executor.rb	Extracted job_class from payload and wrapped core execute flow in Instrumentation.instrument("pgbus.executor.execute", queue:, job_class:) block; adjusted subsequent job-completed instrumentation to use local job_class.
Instrumented Serializer lib/pgbus/serializer.rb	Wrapped serialize_job and deserialize_job in Instrumentation.instrument blocks emitting pgbus.serializer.* events with kind: :job.
Allocation Budget Tests spec/pgbus/allocation_budget_spec.rb	New RSpec file using MemoryProfiler to assert allocation budgets and absence of retained objects for client/serialization/read operations.

Sequence Diagram(s)

sequenceDiagram
  participant Client as Client
  participant PGMQ as PGMQ
  participant Instrument as Instrumentation
  participant Serializer as Serializer
  participant Executor as Executor

  Client->>Instrument: instrument("pgbus.client.send_message", queue:)
  Instrument-->>Client: yield
  Client->>Serializer: serialize_job(job)
  Serializer->>Instrument: instrument("pgbus.serializer.serialize", kind: :job)
  Instrument-->>Serializer: yield
  Serializer-->>Client: serialized_payload
  Client->>PGMQ: produce(serialized_payload)
  Client-->>Instrument: instrumentation complete

  Executor->>Instrument: instrument("pgbus.executor.execute", queue:, job_class:)
  Instrument-->>Executor: yield
  Executor->>PGMQ: read_message
  PGMQ-->>Executor: message
  Executor->>Serializer: deserialize_job(payload)
  Serializer->>Instrument: instrument("pgbus.serializer.deserialize", kind: :job)
  Instrument-->>Serializer: yield
  Serializer-->>Executor: job_instance
  Executor->>Executor: execute_job(job_instance)
  Executor->>PGMQ: archive_message
  Executor-->>Instrument: instrumentation complete

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Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• feat: concurrency controls (Phase 6) #8: Modifies lib/pgbus/active_job/executor.rb, overlapping with the executor instrumentation and job_class extraction changes.
• test: comprehensive unit test coverage for all lib modules #6: Changes to lib/pgbus/client.rb and related client tests; related to client instrumentation additions here.
• feat: batch support (Phase 7) #9: Also edits Pgbus::ActiveJob::Executor#execute (batch lifecycle/signaling), touching the same execute flow modified in this PR.

Poem

🐰
I hopped through code with tiny feet,
Measured bytes and beats per beat,
JSON twirled and jobs took flight,
Memory danced in morning light.
Benchmarks hum — a carrot treat! 🥕

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately captures the main changes: adding instrumentation, benchmarks, and allocation budgets to improve performance observability and testing.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@benchmarks/memory_profile.rb`:
- Around line 69-76: Fix the incorrect hash-style access to MemoryProfiler Stat
objects in memory_profile.rb: replace stat[:count] and stat[:memory] with the
Stat method accessors (stat.count and stat.memsize) and stop using stat[:data];
instead pull the gem or location label from the grouping returned by
report.retained_memory_by_gem / report.retained_memory_by_location (e.g.,
iterate with |gem_name, stats| or |location, stats| and then use stat.count and
stat.memsize for each Stat). Ensure you update the puts lines to use the
gem_name/location label plus stat.count and stat.memsize.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: ff370d0b-2d84-43f9-a266-0a80a7a23f56

📥 Commits

Reviewing files that changed from the base of the PR and between 31fd277 and e90434c.

📒 Files selected for processing (12)

• Gemfile
• Rakefile
• benchmarks/bench_helper.rb
• benchmarks/client_bench.rb
• benchmarks/executor_bench.rb
• benchmarks/memory_profile.rb
• benchmarks/serialization_bench.rb
• lib/pgbus/active_job/executor.rb
• lib/pgbus/client.rb
• lib/pgbus/instrumentation.rb
• lib/pgbus/serializer.rb
• spec/pgbus/allocation_budget_spec.rb