Parallel Collector GC Log Message Format

This section provides examples of HotSpot Parallel Collector GC log messages.

Different garbage collectors also generate different log messages. Here is an example of log messages generated by the Parallel Collector:

C:\>\progra~1\java\jdk1.8.0\bin\java -Xms2m -Xmx64m -XX:+UseParallelGC
   -XX:+PrintGCDetails GarbageCollection

   [GC (Allocation Failure) 
      [PSYoungGen: 450K->248K(768K)] 
      0.0035187 secs] 
   [Times: user=0.00 sys=0.00, real=0.00 secs] 
   -- Minor GC. 
      PSYoungGen stands for Parallel Scavenge Young Generation

1   1835008   472000   1363008

   [GC (Allocation Failure) 
      [PSYoungGen: 731K->240K(768K)] 
      0.0039119 secs] 
   [Times: user=0.00 sys=0.00, real=0.00 secs] 

   [Full GC (Ergonomics) 
      [PSYoungGen: 240K->0K(768K)] 
      [ParOldGen: 1828K->2037K(3840K)] 
      [Metaspace: 44K->44K(4480K)], 
      0.0642066 secs] 
   [Times: user=0.05 sys=0.00, real=0.07 secs] 
   -- Full GC.
      ParOldGen stands for Parallel Old Generation

2   4718592   2347656   2370936


 PSYoungGen      total 14592K, used 2379K [0x068c0000, 0x07e00000...
  eden space 7424K, 32% used [0x068c0000,0x06b12eb0,0x07000000)
  from space 7168K, 0% used [0x07700000,0x07700000,0x07e00000)
  to   space 7168K, 0% used [0x07000000,0x07000000,0x07700000)
 ParOldGen       total 43776K, used 32474K [0x03e00000, 0x068c000...
  object space 43776K, 74% used [0x03e00000,0x05db6a80,0x068c0000)
 Metaspace used 45K, capacity 2242K, committed 2368K, reserved 4480K

As you can see, the Parallel Collector log message format is identical to the Serial Collector, except that different GC algorithms are used on Young Generation and on Tenured (Old) Generation.

The Parallel Collector does not include timestamps in the log messages. So you have to add it by using "–XX:+PrintGCTimeStamps" option.

Last update: 2014.

Table of Contents

 About This Book

 Downloading and Installing JDK 1.8.0 on Windows

 Downloading and Installing JDK 1.7.0 on Windows

 java.lang.Runtime Class - The JVM Instance

 java.lang.System Class - The Operating System

 ClassLoader Class - Class Loaders

 Class Class - Class Reflections

 Sun's JVM - Java HotSpot VM

 JRockit JVM 28.2.7 by Oracle Corporation

 JVM Runtime Data Areas

Memory Management and Garbage Collectors

 Memory Management General Rules

 Java Exception: "java.lang.OutOfMemoryError: Java heap space"

 OutOfMemoryError Comparison of HotSpot and JRockit

 Garbage Collection Demonstration

 JVM Memory Manager - Garbage Collector

 Generational Garbage Collection in HotSpot

 Young Generation Collection - Minor Collection

 Tenured Generation Collection - Full Collection

 HotSpot Default Garbage Collector - Serial Collector

 "-XX:+PrintGCDetails" - Garbage Collection Logging

 GC Log Messages on

 Serial, Parallel, Concurrent, and Regionalized Collectors

Parallel Collector GC Log Message Format

 Parallel Compacting Collector GC Log Message Format

 Concurrent Mark-Sweep Collector GC Log Message Format

 Garbage First GC Log Message Format

 Garbage Collection Tests

 JVM Stack, Frame and Stack Overflow

 Thread Testing Program and Result

 CPU Impact of Multi-Thread Applications

 I/O Impact of Multi-Thread Applications

 CDS (Class Data Sharing)

 Micro Benchmark Runner and JVM Options

 Micro Benchmark Tests on "int" Operations

 Micro Benchmark Tests on "long" Operations

 Micro Benchmark Tests in JIT Compilation Mode

 Micro Benchmark Tests on "float" and "double" Operations

 Outdated Tutorials


 PDF Printing Version