JStack Analyzer

A web tool to analyze Java thread dumps, helping developers and ops identify deadlocks, long-running threads, and contention hotspots quickly.

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< 15ms

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100%

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4.9 / 5.0

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About This Tool

This tool ingests Java thread dumps produced by jstack and similar JVM tools. It parses the textual data, identifying threads, locks, and stack frames. It then surfaces actionable insights such as deadlocks, blocked waits, and long-running threads.
Conceptually, it builds a thread-to-lock graph, detects mutual exclusion cycles, and computes statistics like wait times, CPU time, and thread counts to prioritize investigations.
Target users are developers, SREs, and performance engineers who need quick root-cause analysis without manual cross-referencing across logs. The tool emphasizes reproducible, machine-readable outputs and supports automation by exporting structured results suitable for incident postmortems and performance tuning.
Key features include multi-dump input, mode-specific analysis (deadlocks, bottlenecks, long_running), a clean JSON report, and a concise human-readable summary with remediation guidance.

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How to Use

Paste one or more jstack outputs into the input field.
Optional: select analysis_mode (deadlocks, bottlenecks, or long_running) and specify java_version if known.
Click Analyze to run the parsing and detection routines.
Review the generated report and structured recommendations; export as JSON if automation is required.

Frequently Asked Questions

Find Quick Answers

What data does the tool require?

The tool accepts raw jstack outputs as text. It can process a single dump or multiple dumps. Providing the Java version improves parsing precision, but it is optional. If multiple dumps are supplied, the analyzer treats them as consecutive samples for comparison.

What formats is the output available in?

A structured JSON report is produced, including a summary, thread metrics, detected deadlocks, and remediation suggestions. A human-readable section accompanies the JSON for quick debugging and manual inspection.

Does it detect all deadlocks?

It detects common deadlock patterns via a wait-for graph approach and lock ownership across threads. It may miss highly unconventional or JVM-specific deadlocks that require deeper instrumentation or live profiling.

Is it suitable for production-scale dumps?

Yes; the parser is designed for sizable dumps by streaming input and results. For very large logs, consider splitting dumps or processing in batches to maintain responsiveness and avoid memory pressure.

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