Benchmark: Gitaly with Raft, Reftables and Transactions

Objective

Benchmark Gitaly with Raft + Reftabled + Transactions enabled.

Scope

• Baseline: Gitaly
• Variant: Gitaly with Raft + Reftables + Transactions enabled
• Workloads: clone/fetch, push/write (small/large), RPC hot paths, GC/pack, repo create/delete, mixed read/write, concurrency scaling (repos × RPCs)
• EXT4 FS

Configuration:

To be declared in each gitaly instance block

 config:
      # Whether transactions should be enabled.
      transactions: true
      raft: true

To enable reftables for a specific repo, initialize the test repo within the repositories block in config.yml with

reference_backend: reftable

Test Matrix

• Concurrency:
  • Repos: 1...5
  • Parallel RPCs per repo: 1, 8, 32
• Repository shapes:
  • Small repos (many loose objects/files)
  • Medium repos (Decent number of commits, trees, branches)
  • Large monorepos (large packfiles, deep history)
• Raft Enabled
• Transactions Enabled
• Reftables Enabled/Disabled
• Cache state:
  • Cold-cache (drop_caches) vs steady-state warm cache

Documentation Requirements

• Follow standardized results template

Deliverables

• Reproducible benchmark runs using the framework from #6732
• Comparison tables/plots: baseline vs Transactions (per workload and concurrency level)
• Analysis summarizing:
  • bottlenecks
  • snapshot latencies and impact of files and directories on snapshot performance
  • p95 latency per RPC
  • impact of large number of refs
• Artifact bundle per run: raw results (JSON/CSV), system profile, flamegraphs
• Summary published to this issue with links to artifacts