Concurrency Review
Reviews Java concurrent code for races, deadlocks, visibility, and virtual-thread patterns
Test report
- Verdict
- Tested · Works
- Score
- Tested
- Jul 21, 2026
- Environment
- Claude Code 2.x (agent harness)
- Upstream re-checked
- Aug 10, 2026 · 198f492
Fetched SKILL.md and README raw from the repo; frontmatter parses with valid name+description and the body is self-contained (only grep analysis commands, no referenced scripts/files to break, no security smells). Trigger: judged 3 activating phrasings ("do a concurrency review of my ExecutorService code", "check thread safety of this shared counter", "review my @Async Spring service for race conditions" — all YES) and 2 adjacent non-activating ("review this Java class for clean code and naming", "optimize the SQL query performance" — both NO); 5/5 correct. Output: wrote a 28-line buggy BankService.java, then produced baseline_review.md (no skill) and skill_review.md (following the checklist). Baseline caught the same 5 core bugs (non-atomic long, missing volatile, DCL, HashMap race, deadlock); the skill artifact added severity triage buckets, a concrete order-by-getId deadlock fix vs baseline's vague "possible deadlock", a modern-Java section, and grep sweep commands — a real but moderate improvement, hence 6.
Scored on four weighted criteria — install, triggering, output vs. baseline, docs. How scoring works
- Installs cleanly 5/5
- Triggers reliably 5/5
- Output vs. baseline 6/10
- Docs & honesty 4/5
What Concurrency Review does
A knowledge-and-checklist skill that reviews Java multithreaded code for thread safety: check-then-act races, missing volatile/visibility, broken double-checked locking, deadlock lock-ordering, unsafe collections, Spring @Async proxy pitfalls, CompletableFuture error handling, and Java 21/25 virtual-thread and structured-concurrency patterns. Triggers when the user asks for a concurrency review, thread-safety check, or async code review, or when reviewing code using synchronized, volatile, ExecutorService, or @Async.
How to install Concurrency Review
git clone --depth 1 https://github.com/decebals/claude-code-java.git /tmp/concurrency-review-src
mkdir -p ~/.claude/skills
cp -R /tmp/concurrency-review-src/.claude/skills/concurrency-review ~/.claude/skills/concurrency-review
# Self-contained knowledge skill: SKILL.md + README.md only, no scripts, no external deps.
# Body uses plain grep commands for analysis; nothing to install or configure.
Skills live in ~/.claude/skills/ (global) or .claude/skills/
(per-project). Restart Claude Code after installing.
Commands — how to trigger Concurrency Review
-
/concurrency-reviewReviews Java concurrent code for races, deadlocks, visibility, and virtual-thread patterns
It also activates on plain-language prompts like these:
-
Check this code for thread safety issues -
Review this CompletableFuture chain for deadlocks -
Audit this @Async method for race conditions
Frequently asked questions
- Is the Concurrency Review skill free?
- Yes. The skill itself is free from decebals/claude-code-java. SkillProof publishes the install command and an independent test verdict at no cost.
- Does Concurrency Review work with Claude Code?
- We tested it with Claude Code 2.x (agent harness) on Jul 21, 2026. Verdict: Tested · Works. Fetched SKILL.md and README raw from the repo; frontmatter parses with valid name+description and the body is self-contained (only grep analysis commands, no referenced scripts/files to break, no security smells). Trigger: judged 3 activating phrasings ("do a concurrency review of my ExecutorService code", "check thread safety of this shared counter", "review my @Async Spring service for race conditions" — all YES) and 2 adjacent non-activating ("review this Java class for clean code and naming", "optimize the SQL query performance" — both NO); 5/5 correct. Output: wrote a 28-line buggy BankService.java, then produced baseline_review.md (no skill) and skill_review.md (following the checklist). Baseline caught the same 5 core bugs (non-atomic long, missing volatile, DCL, HashMap race, deadlock); the skill artifact added severity triage buckets, a concrete order-by-getId deadlock fix vs baseline's vague "possible deadlock", a modern-Java section, and grep sweep commands — a real but moderate improvement, hence 6.
- What is the Concurrency Review SkillProof Score?
- 8.0/10 — installs cleanly 5/5, triggers reliably 5/5, output vs. baseline 6/10, docs & honesty 4/5.
- How do I install Concurrency Review?
- Copy the install command from this page, run it in your terminal, and restart Claude Code. Skills live in ~/.claude/skills/ (global) or .claude/skills/ inside a project.
- Can I use Concurrency Review with Cursor, Copilot, Gemini CLI, Codex or other AI tools?
- The SKILL.md format is native to Claude (Claude Code, Desktop, claude.ai). The instructions inside adapt to other assistants: Cursor rules, GitHub Copilot instructions, Windsurf rules, Custom GPTs, AGENTS.md for OpenAI Codex, and GEMINI.md for Google Gemini CLI — our conversion guides cover each, and the free converter on the tools page does the wrapping for you.