This tab contains all the verbose stats & graphs about GC pauses - Young/Tenured/Full collections, split on STW (Stop-The-World) and Concurrent; percentiles and etc.

Percentiles shows the distribution of STW pauses by the percent of occurrence:

For example, line 99% | 117.416 means that 99% of STW events are under 117.416 milliseconds.

GCPlot can also calculate very useful average rates for the selected interval, like in the next example:

This means that for each minute the cumulative average STW pause is ~853 ms, which is produced by ~22 events. In other words, for each 60 seconds the application is fully stopped for ~853 ms.

There are also four graphs:

  • Pause Durations (Stop-The-World only) - GC pauses in milliseconds

  • Log(x) Pause Durations (Stop-The-World only) - Log10(x) of GC pauses, which is very helpful for seeing distribution of low values

  • Concurrent Phase Durations (Non-STW) - concurrent collections durations in milliseconds (if available)

  • Log(x) Concurrent Phase Durations (Non-STW) - Log10(x) of concurrent durations (if available)

These are examples of such graphs built from some log file:

And finally you can see how much time does STW and Concurrent collections took relatively to the time where application-only was running:

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