Java GC Log Analysis

Question

I am new to gc log.

What is the meaning of the next gc log. Does this mean any useful information?

16960.890: [GC [PSYoungGen: 111960K->36400K(523584K)] 845053K->770190K(1286720K), 0.0270419 secs] [Times: user=0.13 sys=0.00, real=0.03 secs] 16960.917: [Full GC (System) [PSYoungGen: 36400K->0K(523584K)] [PSOldGen: 733789K->714479K(763136K)] 770190K->714479K(1286720K) [PSPermGen: 34154K->34154K(38208K)], 1.0982179 secs] [Times: user=1.09 sys=0.00, real=1.09 secs] 

What does PSYoundGen mean? What does the Full GC line mean? I am looking for it on Google, but do not understand it clearly. thanks for the answer!

Answer 1

PSYoungGen refers to the garbage collector used for the minor collection. PS stands for Parallel Scavenge.

Link: Java garbage message log messages

Answer 2

An image can tell a thousand words. It will be much easier to interpret your GC logs visually. I found GCViewer very useful in the past, including links to related topics.

Answer 3

I would use a graphical tool to analyze the file. It is difficult to draw conclusions from raw data. See Know any garbage collection log analysis tools?

Answer 4

JSM HotSpot's excellent memory management white paper will answer most of the questions that may arise on the topic.

Answer 5

GC logs are vital artifacts for troubleshooting memory / CPU issues and optimizing application performance.

Enable java 9 GC Logs

To enable GC logging in Java 9, a new system property has been introduced. You need to pass this system property during application startup:

-Xlog: ds *: file =

Example:

-Xlog: ds *: File = / tmp / logs / gc.log

Analysis tools

The format of the GC log is completely changed in Java 9. For the analysis of GC logs in Java 9, it is highly recommended to use GC log analysis tools such as GCeasy, HPJmeter. These tools analyze java 9 GC logs and generate excellent graphical data visualization, reports on key performance indicators and a number of other useful metrics.