Borrowing it
Nothing to install: this file belongs to eclipse-rdf4j/rdf4j. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/eclipse-rdf4j/rdf4j/main/.agent/skills/high-performance-java/SKILL.mdgit clone --depth 1 https://github.com/eclipse-rdf4j/rdf4jWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/eclipse-rdf4j/rdf4j/high-performance-java)<a href="https://agentmods.dev/skills/eclipse-rdf4j/rdf4j/high-performance-java"><img src="https://agentmods.dev/badge/skills/eclipse-rdf4j/rdf4j/high-performance-java/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/eclipse-rdf4j/rdf4j/high-performance-java"><img src="https://agentmods.dev/badge/skills/eclipse-rdf4j/rdf4j/high-performance-java.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Excessive Agency · line 48 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00140 | $0.02392 |
| Opus 5.5 | $0.00056 | $0.00957 |
| Sonnet 5.5 | $0.00028 | $0.00478 |
| Haiku 4.5 | $0.00014 | $0.00239 |
Grade A, and why
high-performance-java scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 195 lines — stays where its author put it; the contents beside it link to each section on GitHub.
High-Performance Java
Use this skill for Java hot paths, algorithm-heavy Java, and JVM-side runtime specialization. Default bias: asymptotic win first, then the right execution model, then fewer allocations, fewer copies, less polymorphism, narrower code shape, stronger evidence.
HotSpot-only v1. Baseline assumptions:
- repo baseline: JDK 21
- current local runtime may be newer
- low-level claims stay provisional until benchmark + JIT evidence agree
- algorithm/data-structure claims stay provisional until they match the actual workload constraints
- runtime codegen claims stay provisional until cold-start cost, warm steady-state behavior, and fallback behavior are all understood
Core loop
- Identify the workload shape and constraints.
- Pick the algorithm and data structure that change the slope.
- Decide whether the workload should stay interpreted, become vectorized/batched, or justify runtime specialization/code generation.
- Find the hot loop, hot call chain, or hot operator pipeline.
- Write the narrow fast path first.
- Push generic abstraction, materialization, and dispatch out of the loop.
- Benchmark before claiming improvement.
- Inspect HotSpot decisions before claiming JVM-level reasons.
Default coding bias
- Prefer an algorithmic win over a micro win.
- Prefer data structures that fit the operation mix, memory budget, and key domain.
- Prefer the right execution model over reflexively adding code generation.
- Prefer primitive-friendly layouts before boxed object graphs.
- Prefer zero-copy over copy-transform-copy.
- Prefer reuse over per-item allocation.
- Prefer lazy traversal over full materialization.
- Prefer primitives, flat arrays, and tight counted loops in hot paths.
- Prefer monomorphic calls that inline away.
- Prefer specialized lambda/adaptor code for the active workload.
- Prefer one fast path plus one cold fallback over a single generalized hot path.
- Prefer Janino only when generated Java can stay simple, code size can stay bounded, and compile cost can be amortized.
What ships with it
8 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- agents/openai.yaml 376 B
- references/advanced-coding-techniques.md 6.0 KB
- references/algorithms-data-structures.md 7.0 KB
- references/codegen-and-janino.md 9.4 KB
- references/coding-rules.md 3.5 KB
- references/evidence-workflow.md 2.7 KB
- references/high-performance-java-libraries.md 7.3 KB
- references/jdk-21-26-notes.md 1.4 KB
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 195 lines · 140 tokens per session scan A 56bdf6776673
high-performance-java is a skill published in the GitHub repository eclipse-rdf4j/rdf4j (422 stars, last pushed today), licensed BSD-3-Clause. It adds 140 tokens to every session and 2,392 once invoked, about $0.0006 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
Other skills, from other repositories
open-ontologies
AI-native ontology engineering using 110 MCP tools backed by an in-memory Oxigraph triple store. Build, validate, query, and govern RDF/OWL ontologies with a generate-validate-iterate loop. Use when building ontologies, knowledge graphs, RDF data, SPARQL queries, BORO/4D modeling, SHACL validation, clinical…
mcp-sparql
Exposes SPARQL query capabilities to LLMs via the Model Context Protocol. Supports SELECT, ASK, CONSTRUCT, and DESCRIBE queries against any SPARQL endpoint.
814-regulations-iso-25010
Use when reviewing, designing, or modifying Java enterprise systems and need a structured, repeatable ISO/IEC 25010:2023 quality-attribute review covering Functional Suitability, Performance Efficiency, Compatibility, Interaction Capability, Reliability, Security, Maintainability, Flexibility, and Safety, producing an…
121-java-object-oriented-design
Use when reviewing, improving, or refactoring Java object-oriented design, including applying SOLID, DRY, or YAGNI; improving classes and interfaces; correcting encapsulation, inheritance, or polymorphism; resolving God Class, Feature Envy, or Data Clumps; and improving object creation, methods, or exception…
053-design-simple-rules
Use when Java design, refactoring, or implementation tradeoffs should be evaluated with Kent Beck's simple design rules, including passes the tests, reveals intention, has no duplication, and has the fewest elements. This should trigger for requests such as Apply simple design rules; Review this design with Beck's…
solid-principles
SOLID principles checklist with Java examples. Use when a class has too many responsibilities, an abstraction leaks, or a dependency points the wrong way, and when the user asks about Single Responsibility, Open/Closed, Liskov, Interface Segregation or Dependency Inversion. For naming, duplication and method length…