GC Log Analysis ​

Introduction ​

GC (Garbage Collection) log analysis is a technical approach used to analyze issues related to garbage collection. When Java applications experience long pauses and response-time (RT) jitter caused by GC, GC logs can provide detailed information about the causes, duration, memory changes, and other relevant details.

Different versions of the JDK and various GC algorithms have different log formats, and there is a series of JVM options controlling the level of detail, making it more challenging to analyze logs directly. Using GC log analysis can help developers quickly identify issues such as memory leaks, long pauses, premature object promotions, and other performance-affecting problems. This feature also provides comparative analysis views, which can guide developers in optimizing GC performance and understanding the impact of code or JVM option changes on GC performance.

Views ​

Basic Information ​

This view displays some basic information, such as the GC algorithm used by the application, the number of GC threads, and the time period covered by the log.

Diagnosis ​

This view analyzes the serious issues present in the application and marks them on a timeline. It also provides information about the most critical problems that need to be addressed first, including the exact time they occurred and general troubleshooting and optimization methods.

Time Graph ​

This view presents data such as GC duration and memory changes in various regions through visual representation.

Pause Info ​

This view displays metrics related to GC pauses, such as average pause time and maximum pause time.

Heap and Metaspace ​

This view presents memory usage of the metaspace and each region of the heap.

Phase and Cause ​

This view is split based on GC phases or causes, displaying metrics such as the number of occurrences, intervals, and durations.

Object Statistics ​

This view displays data related to object creation and promotion.

JVM Options ​

This view displays the JVM options used by the application.

Log Details ​

This view displays the details of each GC and supports querying based on dimensions such as the cause.