fabric-pyspark-perf-remediate

fabric-pyspark-perf-remediate is a skill for Claude Code, Codex from PatrickGallucci/fabric-skills. It costs 179 tokens per session (2,130 once invoked), scanned A, original, MIT.

A troubleshooting guide for PySpark performance in Microsoft Fabric notebooks and Spark jobs. PySpark is Python code that runs on Apache Spark to process large datasets.

In plain words
What is it for?
Use it to investigate slow cells or jobs, out-of-memory errors, uneven workloads, excessive shuffling, slow Delta Lake writes, small files, and throttled or queued capacity.
Why use it?
It helps connect slow jobs and failures to memory use, data imbalance, excessive data movement, storage layout, or limited Fabric capacity.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to investigate slow cells or jobs, out-of-memory errors, uneven workloads, excessive shuffling, slow Delta Lake writes, small files, and throttled or queued capacity.

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Install with agentmods
npx agentmods add skills/patrickgallucci/fabric-skills/fabric-pyspark-perf-remediate
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add PatrickGallucci/fabric-skills --skill fabric-pyspark-perf-remediate
Clone the repo
git clone --depth 1 https://github.com/PatrickGallucci/fabric-skills

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for fabric-pyspark-perf-remediate

README.md
[![agentmods](https://agentmods.dev/badge/skills/patrickgallucci/fabric-skills/fabric-pyspark-perf-remediate/github.svg)](https://agentmods.dev/skills/patrickgallucci/fabric-skills/fabric-pyspark-perf-remediate)
Your own site
<a href="https://agentmods.dev/skills/patrickgallucci/fabric-skills/fabric-pyspark-perf-remediate"><img src="https://agentmods.dev/badge/skills/patrickgallucci/fabric-skills/fabric-pyspark-perf-remediate/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.

agentmods 80×15 button for fabric-pyspark-perf-remediate

Your own site · 80×15
<a href="https://agentmods.dev/skills/patrickgallucci/fabric-skills/fabric-pyspark-perf-remediate"><img src="https://agentmods.dev/badge/skills/patrickgallucci/fabric-skills/fabric-pyspark-perf-remediate.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 179 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,130 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00179 $0.02130
Opus 5 $0.00089 $0.01065
Sonnet 5 $0.00036 $0.00426
Haiku 4.5 $0.00018 $0.00213

Measured 13d ago against content hash e6d9d1a9df0b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

fabric-pyspark-perf-remediate 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 13d ago.

The scan reads SKILL.md. This mod also ships 4 executable files (scripts/delta_table_health.py, scripts/identify_skew.py, scripts/spark_health_check.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/fabric-pyspark-perf-remediate/SKILL.md · 157 lines

How it starts

The opening of the file, as written. The whole thing — 157 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Microsoft Fabric PySpark Performance remediate

Systematic guide for diagnosing and resolving Apache Spark performance problems in Microsoft Fabric Data Engineering workloads, including notebooks, Spark Job Definitions, and pipeline activities.

When to Use This Skill

Activate when encountering any of these scenarios:

  • PySpark notebook cells take unexpectedly long to execute
  • Spark Job Definitions exceed expected duration or fail with timeouts
  • Out-of-memory (OOM) errors on driver or executors
  • Excessive shuffle read/write in Spark UI stage details
  • Data skew causing individual tasks to run much longer than peers
  • Delta Lake table writes are slow or produce many small files
  • Fabric capacity utilization is high or jobs are queued/throttled
  • Need to choose between resource profiles (readHeavy vs writeHeavy)
  • Deciding whether to enable autotune, native execution engine, or Optimized Write
  • Interpreting Spark UI metrics (stages, tasks, storage, SQL plan)

Prerequisites

  • Access to a Microsoft Fabric workspace with Data Engineering/Science experience
  • Fabric capacity (F2 or higher) with Spark compute enabled
  • Familiarity with PySpark DataFrames and Spark SQL
  • Access to Spark UI via the Monitoring Hub or notebook session details

Quick Diagnostic Workflow

Follow this triage sequence to identify the root cause:

  1. Check capacity status - Is the Fabric capacity throttled or overloaded? See Monitoring Hub for queued jobs and CU utilization.
  2. Identify the slow stage - Open Spark UI, find the stage with the longest duration, and check task-level metrics.
  3. Classify the bottleneck - Use the decision matrix below to categorize the issue.
  4. Apply targeted fix - Follow the relevant reference guide for your bottleneck type.
  5. Validate improvement - Re-run the job and compare Spark UI metrics before and after.

Bottleneck Decision Matrix

Use these indicators to classify your performance issue:

Shuffle Bottleneck: Shuffle read/write bytes are large (>1 GB per stage), many tasks in the stage, high GC time. Fix with broadcast joins, reduced shuffle partitions, or pre-partitioned data. See shuffle-and-join-optimization.md.

Read the full file on GitHub · 157 lines

Changes

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.

  1. 13d ago First seen · 157 lines · 179 tokens per session scan A e6d9d1a9df0b

Subscribe to this mod's changes

fabric-pyspark-perf-remediate is a skill published in the GitHub repository PatrickGallucci/fabric-skills (16 stars, last pushed 3mo ago), licensed MIT. It adds 179 tokens to every session and 2,130 once invoked, about $0.0009 per session on Opus 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 2026-08-30.

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