How to redirect verbose garbage collection output to a file

Question

How do I redirect verbose garbage collection output to a file   Sun   s website shows an example for Unix but it doesn t work for Windows

User · Accepted Answer

From the output of java -X       -Xloggc  lt file     log GC status to a file with time stamps  Documented here   -Xloggc filename Sets the file to which verbose GC events information should be redirected for logging  The information written to this file is similar to the output of -verbose gc with the time elapsed since the first GC event preceding each logged event  The -Xloggc option overrides -verbose gc if both are given with the same java command  Example      -Xloggc garbage-collection log  So the output looks something like this   0 590   GC 896K- 278K 5056K   0 0096650 secs  0 906   GC 1174K- 774K 5056K   0 0106856 secs  1 320   GC 1670K- 1009K 5056K   0 0101132 secs  1 459   GC 1902K- 1055K 5056K   0 0030196 secs  1 600   GC 1951K- 1161K 5056K   0 0032375 secs  1 686   GC 1805K- 1238K 5056K   0 0034732 secs  1 690   Full GC 1238K- 1238K 5056K   0 0631661 secs  1 874   GC 62133K- 61257K 65060K   0 0014464 secs

User · Answer

Java 9  amp  Unified JVM Logging  JEP 158 introduces a common logging system for all components of the JVM which will change  and IMO simplify  how logging works with GC  JEP 158 added a new command-line option to control logging from all components of the JVM    -Xlog   For example  the following option   -Xlog gc   will log messages tagged with gc tag using info level to stdout  Or this one   -Xlog gc debug file gc txt none   would log messages tagged with gc tag using debug level to a file called gc txt with no decorations  For more detailed discussion  you can checkout the examples in the JEP page

User · Answer

If in addition you want to pipe the output to a separate file  you can do   On a Sun JVM   -Xloggc C  whereever jvm log -verbose gc -XX  PrintGCDateStamps   ON an IBM JVM   -Xverbosegclog C  whereever jvm log

User · Answer

To add to the above answers  there s a good article  Useful JVM Flags     Part 8  GC Logging  by Patrick Peschlow   A brief excerpt   The flag -XX  PrintGC  or the alias -verbose gc  activates the    simple    GC logging mode  By default the GC log is written to stdout  With -Xloggc  lt file gt  we may instead specify an output file  Note that this flag implicitly sets -XX  PrintGC and -XX  PrintGCTimeStamps as well   If we use -XX  PrintGCDetails instead of -XX  PrintGC  we activate the    detailed    GC logging mode which differs depending on the GC algorithm used   With -XX  PrintGCTimeStamps a timestamp reflecting the real time passed in seconds since JVM start is added to every line   If we specify -XX  PrintGCDateStamps each line starts with the absolute date and time

[garbage-collection] How to redirect verbose garbage collection output to a file?

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