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jfr(1)                           JDK Commands                           jfr(1)




NAME

       jfr - parse and print Flight Recorder files


SYNOPSIS

       To print the contents of a flight recording to standard out:

       jfr print [options] file

       To print metadata information about flight recording events:

       jfr metadata file

       To assemble chunk files into a flight recording file:

       jfr assemble repository file

       To disassemble a flight recording file into chunk files:

       jfr disassmble [options] file

       To view the summary statistics for a flight recording file:

       jfr summary file

       options
              Optional:  Specifies  command-line  options separated by spaces.
              See the individual subcomponent sections for descriptions of the
              available options.

       file   Specifies the name of the target flight recording file (.jfr).

       repository
              Specifies the location of the chunk files which are to be assem-
              bled into a flight recording.


DESCRIPTION

       The jfr command provides a tool for interacting  with  flight  recorder
       files  (.jfr).   The  main  function is to filter, summarize and output
       flight recording files into human readable format.  There is also  sup-
       port for merging and splitting recording files.

       Flight recording files are created and saved as binary formatted files.
       Having a tool that can extract the contents from a flight recording and
       manipulate  the  contents and translate them into human readable format
       helps developers to debug performance issues with Java applications.

   Subcommands
       The jfr command has several subcommands:

       o print

       o summary

       o assemble

       o disassemble

       o metadata

   jfr print subcommand
       Use jfr print to print the contents of a flight recording file to stan-
       dard out.  The syntax is:

       jfr print  [--xml|--json] [--categories <filters>] [--events <filters>]
       [--stack-depth <depth>] <file>

       where:

       --xml  Print the recording in XML format

       --json Print the recording in JSON format

       --categories <filters>
              Select events matching a category name.  The filter  is  a  com-
              ma-separated  list  of  names,  simple  and/or qualified, and/or
              quoted glob patterns

       --events <filters>
              Select events matching an event name.   The  filter  is  a  com-
              ma-separated  list  of  names,  simple  and/or qualified, and/or
              quoted glob patterns

       --stack-depth <depth>
              Number of frames in stack traces, by default 5

       <file> Location of the recording file (.jfr)

       The default format for printing the contents of  the  flight  recording
       file  is  human  readable  form unless either xml or json is specified.
       These options provide  machine-readable  output  that  can  be  further
       parsed or processed by user created scripts.

       Use jfr --help print to see example usage of filters.

       To  reduce  the  amount of data displayed, it is possible to filter out
       events or categories of events.  The filter operates  on  the  symbolic
       name  of  an  event, set by using the @Name annotation, or the category
       name, set by using the @Category annotation.  If multiple  filters  are
       used, events from both filters will be included.  If no filter is used,
       all the events will be printed.  If a combination of a category  filter
       and  event filter is used, the selected events will be the union of the
       two filters.

       For example, to show all GC events and the CPULoad event, the following
       command could be used:

       jfr print --categories GC --events CPULoad recording.jfr

       Event  values are formatted according to the content types that are be-
       ing used.  For example, a field with the jdk.jfr.Percentage  annotation
       that has the value 0.52 is formatted as 52%.

       Stack  traces  are by default truncated to 5 frames, but the number can
       be increased/decreased using the --stack-depth command-line option.

   jfr summary subcommand
       Use jfr summary to print statistics for a recording.   For  example,  a
       summary  can illustrate the number of recorded events and how much disk
       space they used.  This is useful for troubleshooting and  understanding
       the impact of event settings.

       The syntax is:

       jfr summary <file>

       where:

       <file> Location of the flight recording file (.jfr)

   jfr metadata subcommand
       Use jfr metadata to view information about events, such as event names,
       categories and field layout within a flight recording file.  The syntax
       is:

       jfr metadata <file>

       where:

       <file> Location of the flight recording file (.jfr)

   jfr assemble subcommand
       Use jfr assemble to assemble chunk files into a recording file.

       The syntax is:

       jfr assemble <repository> <file>

       where:

       <repository>
              Directory where the repository containing chunk files is located

       <file> Location of the flight recording file (.jfr)

       Flight recording information is written in chunks.   A  chunk  contains
       all  of  the information necessary for parsing.  A chunk typically con-
       tains events useful for troubleshooting.  If a JVM should crash,  these
       chunks  can be recovered and used to create a flight recording file us-
       ing this jfr assemble command.  These chunk files are  concatenated  in
       chronological  order  and chunk files that are not finished (.part) are
       excluded.

   jfr disassemble subcommand
       Use jfr disassemble to decompose a flight recording file into its chunk
       file pieces.  The syntax is:

       jfr disassemble [--max-chunks <chunks>] [--output <directory>] <file>

       where:

       --output <directory>
              The location to write the disassembled file, by default the cur-
              rent directory

       --max-chunks <chunks>
              Maximum number of chunks per file, by default 5.  The chunk size
              varies, but is typically around 15 MB.

       --max-size <size>
              Maximum number of bytes per file.

       <file> Location of the flight recording file (.jfr)

       This function can be useful for repairing a broken file by removing the
       faulty chunk.  It can also be used to reduce the size of a file that is
       too  large  to  transfer.   The  resulting  chunk  files  are named my-
       file_1.jfr, myfile_2.jfr, etc.  If needed,  the  resulting  file  names
       will  be  padded with zeros to preserve chronological order.  For exam-
       ple, the chunk file name is myfile_001.jfr if the recording consists of
       more than 100 chunks.

   jfr version and help subcommands
       Use jfr --version or jfr version to view the version string information
       for this jfr command.

       To get help on any of the jfr subcommands, use:

       jfr <--help|help> [subcommand]

       where:

       [subcommand] is any of:

       o print

       o metadata

       o summary

       o assemble

       o disassemble



JDK 15                               2020                               jfr(1)

openjdk 15.0.2 - Generated Tue Feb 23 16:15:13 CST 2021
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