Question 1

How to analyze G1 garbage collector logs with GCViewer?

Accepted Answer

Generate logs with -Xloggc:file -XX:+PrintGCDetails -XX:+PrintGCDateStamps for best results. GCViewer visualizes G1 events like concurrent collections and initial marks, but watch for parsing issues with mixed lines as noted in the README.

Question 2

GCViewer vs GCEasy: which is better for production GC analysis?

Accepted Answer

GCViewer is free, open-source, and offers deep multi-JVM support ideal for on-premises log analysis. GCEasy is a cloud service with automated insights but may involve costs and data privacy concerns. Choose based on your infrastructure and analysis needs.

Question 3

Why does GCViewer fail to parse my Java 11 GC log?

Accepted Answer

Java 11 uses unified logging (-Xlog:gc) which GCViewer only partially supports. Ensure your logging configuration matches the specific formats listed in the README, like -Xlog:gc=info:file='path':tags,uptime,level, or consider older JVM flags for compatibility.

Question 4

How to export GC data from GCViewer for use in Excel?

Accepted Answer

Use the command-line interface with the -t CSV option, e.g., java -jar gcviewer.jar gc.log output.csv -t CSV. This exports event data in comma-separated format that can be easily imported into spreadsheet applications for custom reporting.

Question 5

Can GCViewer handle rotated GC log files from long-running apps?

Accepted Answer

Yes, specify multiple log files separated by semicolons in the command line, as shown in the README: java -jar gcviewer.jar gc.log.0;gc.log.1;gc.log.current summary.csv. This allows batch analysis of rotated logs enabled with -XX:+UseGCLogFileRotation.

Question 6

What do the slope metrics in GCViewer's memory panel indicate?

Accepted Answer

Slope full GC shows the trend of memory consumption after full collections over time, helping detect memory leaks. Slope GC indicates the average increase in memory usage between minor collections, useful for tuning young generation sizes and promotion rates.

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