Code Review Skill
awesome-skills/code-review-skill
Provides comprehensive code review guidance for React 19, Vue 3, Angular 17+, Svelte 5, Rust, TypeScript, Java, Java 8, PHP, Ruby, Rails, Python, Django, FastAPI, Go, C/.NET, Kotlin, Swift, Dart…
Audits the Caffeine cache source for hot-path costs such as allocations, contention and memory layout, reporting only findings tied to specific lines.
Install Caffeine Performance Audit
$ npx skills add ben-manes/caffeine --skill audit-performance -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install ben-manes/caffeine audit-performance --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/ben-manes/caffeine.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/audit-performance .claude/skills/audit-performance && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "audit-performance" agent skill from https://github.com/ben-manes/caffeine/tree/master/.claude/skills/audit-performance into .claude/skills/audit-performance/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "audit-performance", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/ben-manes/caffeine/tree/master/.claude/skills/audit-performanceType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add ben-manes/caffeine --skill audit-performance -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install ben-manes/caffeine audit-performance --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/ben-manes/caffeine.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/skills/audit-performance .agents/skills/audit-performance && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "audit-performance" agent skill from https://github.com/ben-manes/caffeine/tree/master/.claude/skills/audit-performance into .agents/skills/audit-performance/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "audit-performance", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add ben-manes/caffeine --skill audit-performance -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install ben-manes/caffeine audit-performance --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/ben-manes/caffeine.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/skills/audit-performance .cursor/skills/audit-performance && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "audit-performance" agent skill from https://github.com/ben-manes/caffeine/tree/master/.claude/skills/audit-performance into .cursor/skills/audit-performance/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "audit-performance", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/ben-manes/caffeine.git --path .claude/skills/audit-performance--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add ben-manes/caffeine --skill audit-performance -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install ben-manes/caffeine audit-performance --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/ben-manes/caffeine.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/skills/audit-performance .gemini/skills/audit-performance && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "audit-performance" agent skill from https://github.com/ben-manes/caffeine/tree/master/.claude/skills/audit-performance into .gemini/skills/audit-performance/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "audit-performance", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install ben-manes/caffeine audit-performanceInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add ben-manes/caffeine --skill audit-performance -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/ben-manes/caffeine.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/skills/audit-performance .github/skills/audit-performance && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "audit-performance" agent skill from https://github.com/ben-manes/caffeine/tree/master/.claude/skills/audit-performance into .github/skills/audit-performance/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "audit-performance", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add ben-manes/caffeine --skill audit-performance -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install ben-manes/caffeine audit-performance --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/ben-manes/caffeine.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/skills/audit-performance .opencode/skills/audit-performance && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "audit-performance" agent skill from https://github.com/ben-manes/caffeine/tree/master/.claude/skills/audit-performance into .opencode/skills/audit-performance/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "audit-performance", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
audit-performance- GitHub stars
- 18k
- Token cost
- ~559 tokens
- SKILL.md length
- 229 words
- Files
- 1
- Skills in repo
- 33
- Repo updated
- First seen
- Licence
- Apache-2.0
At a glance
Audits the Caffeine cache source for hot-path costs such as allocations, contention and memory layout, reporting only findings tied to specific lines.
- Works in 6 steps: Get Fast Path (highest priority) → Allocation and GC Pressure → Contention and Cache-Line Effects → …
- Reviewing the Caffeine read path for avoidable volatile reads or allocations
- SKILL.md covers Rules, Analysis Areas (priority order) and Output Format
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
This skill directs the agent to review the Caffeine caching library for runtime performance costs on its hot paths. It assumes the code is already heavily optimized, so generic advice is out. The agent must read the actual source, report only findings it can trace to specific lines, account for JIT optimizations such as escape analysis and inlining, and ignore correctness, style and API design.
Analysis areas are ranked. The get fast path comes first, counting volatile reads, calls, branches and allocations. Then come allocation and GC pressure, contention and cache-line effects, the FrequencySketch, worst-case maintenance work on writes, and memory layout such as node size and false sharing. Each finding lists category, location and severity, and if fewer than three real issues turn up the agent says the code is well optimized instead of padding the report.
When your agent uses it
- Reviewing the Caffeine read path for avoidable volatile reads or allocations
- Looking for contention or false sharing in a concurrent cache
- Checking worst-case maintenance work and eviction cost on writes
- Auditing JVM hot paths while ignoring optimizations the JIT already makes
Example prompts
- “Audit the Caffeine get path and list any allocations that survive escape analysis.”
- “Check the FrequencySketch for poor counter locality and expensive hashing.”
- “Review the read buffer and eviction lock for contention problems.”
Requirements
- A checkout of the Caffeine source
Workflow steps
6 steps, taken from the step headings in SKILL.md.
What it can do on your machine
Read from SKILL.md and the folder at commit e972fb0. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Caffeine Performance Audit loads about 559 tokens when it runs. Until then it costs about 25 tokens; SKILL.md has 229 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from ben-manes/caffeine at commit e972fb0, republished under its Apache-2.0 licence (© ben-manes). 229 words, ~559 tokens.
Download SKILL.mdSave it as
.claude/skills/audit-performance/SKILL.md (or your agent's skills folder).- name
- audit-performance
- description
- Audit hot paths for performance inefficiencies (allocations, contention, layout)
- context
- fork
- agent
- auditor
- disable-model-invocation
- true
Audit the Caffeine cache for performance inefficiencies.
Context: Caffeine runs in high-throughput, low-latency JVM services where cache operations occur millions of times per second. The library is already heavily optimized — generic textbook advice is not useful.
Rules
- Read the actual source code before analyzing.
- Only report findings traceable to specific lines.
- Account for JIT compilation. C2 eliminates many apparent inefficiencies: escape analysis, inlining, dead code elimination. Don't flag JIT-optimized issues.
- Ignore correctness, style, and API design. This is purely runtime performance.
- Quality over quantity. Five real findings beat twenty speculative ones.
Analysis Areas (priority order)
1. Get Fast Path (highest priority)
Trace get()/getIfPresent() from entry to return. Count volatile/opaque reads, method calls, branches, allocations. Even one saved volatile read matters.
2. Allocation and GC Pressure
Identify allocations surviving escape analysis on hot paths. Frequency, size, lifetime. Do not flag JIT-eliminated allocations.
3. Contention and Cache-Line Effects
CAS retry rates, cache-line bouncing, graceful vs catastrophic degradation for read buffer, evictionLock, CHM bins, node field updates.
4. FrequencySketch
Counter layout locality, hash computation, reset cost. Accessed every read/write.
5. Maintenance Work
Worst-case work per write, latency spikes, eviction cascades, timer wheel scan cost.
6. Memory Layout
Node object size, pointer indirection depth, false sharing, @Contended opportunities.
Output Format
For each finding:
## [Category] Title
**Location:** file:method (lines X-Y)
**Severity:** negligible | moderate | high
**What happens:** (trace the code path)
**Why it matters:** (quantify)
**JIT considerations:** (will C2 handle this?)
**Proposed fix:** (specific code change)
**Expected benchmark impact:** (JMH prediction)If fewer than 3 real issues, the code is well-optimized. Do not pad the output.
© ben-manes, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in .claude/skills/audit-performance of ben-manes/caffeine.
Open the folder on GitHubat commit e972fb0
Compare with similar skills
Caffeine Performance Audit next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Caffeine Performance Audit this skillben-manes/caffeine | 18k | — | ~559 | Automated safety check: Pass | Apache-2.0 | |
| Code Review Skillawesome-skills/code-review-skill | 2.1k | — | ~2.8k | Automated safety check: Notes | MIT | |
| Coding Standardsapache/shardingsphere | 21k | — | ~2.2k | Automated safety check: Pass | Apache-2.0 | |
| Code Review Specialistluongnv89/claude-howto | 42k | — | ~764 | Automated safety check: Pass | MIT | |
| New Rule for sonar-javaSonarSource/sonar-java | 1.2k | — | ~833 | Automated safety check: Pass | Custom licence | |
| Cross-Language Coding Standardszereight/gitlab-mcp | 2k | 1 repos | ~1.4k | Automated safety check: Pass | MIT |
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Code Review Specialist
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More from ben-manes/caffeine
All 33 skills in this repoCaffeine Cache Optimization Experiments
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Runs controlled JMH experiments on the Caffeine cache to find shared contention and hot-path waste, then reviews correctness and returns a reviewable patch.
Git History Bug Audit
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Audits a module by walking its git history commit by commit, tracking unresolved issues forward, and reporting the ones that survive to HEAD as findings.
Adversarial Codebase Audit
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Runs a hostile review of the Caffeine Java caching library with parallel subagents that get no design docs, then challenges and consolidates their findings.
Audit Sibling Divergence
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Compares code paths that should behave the same, such as sync and async cache methods, and requires a concrete scenario where the two observably disagree.
Climber Step Minimization
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Prices each step of the window climber algorithm by disabling it in turn, to find steps that no longer earn their keep and branches that no longer fire.
Parallel Adversarial Change Review
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Runs three parallel reviewers on a diff or branch, one blind, one design-aware and one matching past bug patterns, then triages their findings.
Related
Works with
Categories
Questions about Caffeine Performance Audit
What does Caffeine Performance Audit do?
Audits the Caffeine cache source for hot-path costs such as allocations, contention and memory layout, reporting only findings tied to specific lines. This skill directs the agent to review the Caffeine caching library for runtime performance costs on its hot paths. It assumes the code is already heavily optimized, so generic advice is out.
When should I use Caffeine Performance Audit?
Caffeine Performance Audit fits situations like: reviewing the Caffeine read path for avoidable volatile reads or allocations; looking for contention or false sharing in a concurrent cache; checking worst-case maintenance work and eviction cost on writes; auditing JVM hot paths while ignoring optimizations the JIT already makes.
How do I install Caffeine Performance Audit in Claude Code?
Run `npx skills add ben-manes/caffeine --skill audit-performance -a claude-code`. Or copy the skill folder (.claude/skills/audit-performance in ben-manes/caffeine) into .claude/skills/audit-performance in your project. Claude Code loads it when a task matches its description.
How do I install Caffeine Performance Audit in Codex?
Run `npx skills add ben-manes/caffeine --skill audit-performance -a codex`. Or copy the skill folder (.claude/skills/audit-performance in ben-manes/caffeine) into .agents/skills/audit-performance in your project. Codex loads it when a task matches its description.
Can I use Caffeine Performance Audit in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add ben-manes/caffeine --skill audit-performance -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/audit-performance, .gemini/skills/audit-performance, .github/skills/audit-performance and .opencode/skills/audit-performance in your project.
What does Caffeine Performance Audit need to run?
SKILL.md names no scripts, command-line tools or credentials: Caffeine Performance Audit is instructions for the agent only. Our summary lists: A checkout of the Caffeine source.
Does Caffeine Performance Audit access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Caffeine Performance Audit safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Caffeine Performance Audit use?
Caffeine Performance Audit is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Caffeine Performance Audit use?
About 559 tokens (SKILL.md is roughly 2.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Caffeine Performance Audit?
Skills that share tags, products or a category with Caffeine Performance Audit: Code Review Skill (awesome-skills/code-review-skill, 2.1k stars), Coding Standards (apache/shardingsphere, 21k stars), Code Review Specialist (luongnv89/claude-howto, 42k stars) and New Rule for sonar-java (SonarSource/sonar-java, 1.2k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Caffeine Performance Audit?
ben-manes (a GitHub user) maintains it in ben-manes/caffeine, which has 17,880 GitHub stars. The repository holds 33 skills in this directory. The repository was last updated on October 6, 2026.
Source: ben-manes/caffeine on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.