GCViewer
A Java tool that visualizes and analyzes verbose garbage collection logs from multiple JVM vendors to help optimize memory performance.
What is GCViewer?
GCViewer is a Java-based visualization and analysis tool for verbose garbage collection logs generated by various JVM implementations. It parses GC output from Sun/Oracle, IBM, HP, and BEA JVMs, presenting heap usage, pause times, and collection events in interactive charts and detailed metrics to help diagnose memory issues and optimize performance.
Java developers, performance engineers, and DevOps professionals who need to analyze and tune garbage collection behavior in production or testing environments, especially those working with Sun/Oracle JDK 1.6+, IBM, HP, or BEA JRockit JVMs.
GCViewer provides a free, specialized tool for deep GC log analysis with multi-JVM support, detailed visualizations, and comprehensive metrics that are often missing from generic monitoring solutions, making it a go-to for JVM memory performance troubleshooting.
Overview
Fork of tagtraum industries' GCViewer. Tagtraum stopped development in 2008, I aim to improve support for Sun's / Oracle's java 1.6+ garbage collector logs (including G1 collector)
Use Cases
Best For
- Analyzing garbage collection pauses and throughput in Java applications
- Visualizing heap usage trends and generation sizes over time
- Tuning JVM memory settings based on actual GC behavior
- Comparing GC performance across different JVM versions or collectors
- Identifying memory leaks or excessive promotion rates in long-running apps
- Batch processing GC logs to generate performance reports
Not Ideal For
- Teams using Java 11+ with default -Xlog:gc output and no custom logging configuration tweaks
- Projects requiring real-time GC monitoring or integration with live APM dashboards
- Environments where GC logs are from unsupported JVM vendors or have malformed, mixed-line entries
- Users needing cloud-native, automated GC insights without manual log file handling
Pros & Cons
Pros
Supports GC logs from Sun/Oracle (including Java 1.6+ and G1), IBM, HP, and BEA JRockit, making it versatile for analyzing legacy and modern Java applications across different vendors.
Provides interactive charts with color-coded events like heap usage, GC pauses, and generation sizes, allowing developers to quickly spot patterns and bottlenecks in verbose logs.
Calculates key indicators such as throughput, pause times, promotion rates, and concurrent collection overhead, with detailed panels for summary, memory, and pause statistics as shown in the README.
Offers multiple output formats including CSV, PLAIN (HPjmeter compatible), SIMPLE (gchisto compatible), and SUMMARY, enabling further analysis or integration with other tools.
Cons
Admits limitations with newer Java unified logging formats and can break on mixed or malformed log lines, requiring specific JVM flag configurations for reliable analysis.
Analyzes static log files only, lacking features for live monitoring or streaming GC data, which restricts use in dynamic, production environments needing immediate insights.
Requires Java 1.8 to run and Maven for building from source, which can be a hurdle for teams on newer Java versions or those seeking lightweight, modern tooling.
Frequently Asked Questions
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