Trace formatter (traceformat)

The trace formatter is a Java™ program that converts binary trace point data in a trace file to a readable form. The formatter requires the TraceFormat.dat and J9TraceFormat.dat files, which contain the formatting templates. The formatter produces a file that contains header information about the VM that produced the binary trace file, a list of threads for which trace points were produced, and the formatted trace points with their time stamp, thread ID, trace point ID, and trace point data.


To use the trace formatter on a binary trace file type:

    traceformat <input_file>  [<output_file>] <parameters>

Where <input_file> is the name of the binary trace file to be formatted, and <output_file> is the name of the output file. If you do not specify an output file, the output file is called input_file.fmt.

The size of the heap that is needed to format the trace is directly proportional to the number of threads present in the trace file. For large numbers of threads the formatter might run out of memory, generating the error OutOfMemoryError. In this case, increase the heap size by using the -Xmx option.


The following <parameters> are available with the trace formatter:

Option Explanation
-datfile=<file1.dat>[,<file2.dat>] A comma-separated list of trace formatting data files. By default, the following files are used:$JAVA_HOME/lib/J9TraceFormat.dat and $JAVA_HOME/lib/TraceFormat.dat
-format_time=yes|no Specifies whether to format the time stamps into human readable form. The default is yes.
-help Displays usage information.
-indent Indents trace messages at each Entry trace point and outdents trace messages at each Exit trace point. The default is not to indent the messages.
-summary Prints summary information to the screen without generating an output file.
-threads=<thread id>[,<thread id>]... Filters the output for the given thread IDs only. thread id is the ID of the thread, which can be specified in decimal or hex (0x) format. Any number of thread IDs can be specified, separated by commas.
-timezone=+|-HH:MM Specifies the offset from UTC, as positive or negative hours and minutes, to apply when formatting time stamps.
-verbose Output detailed warning and error messages, and performance statistics.


The following example shows output from running the trace formatter command:

    C:\test>traceformat sample.trc
    Writing formatted trace output to file sample.trc.fmt
    Processing 0.4921875Mb of binary trace data
    Completed processing of 6983 tracepoints with 0 warnings and 0 errors

The formatted trace output looks similar to the following extract, which is truncated to show the key areas of information:

    Trace Summary

    Service level:
    JRE 1.8.0 Windows 7 amd64-64 build  (pwa6480sr2-20150624_06(SR2))

    JVM startup options:

    Processor information:
    Arch family:         AMD64
    Processor Sub-type:  Opteron
    Num Processors:      8
    Word size:           64

    Trace activation information::

    Trace file header:
    JVM start time: 08:58:35.527000000
    Generations:    1
    Pointer size:   8

    Active threads
    0x000000000f155f00  Attach API wait loop
    0x000000000f18b200  Thread-1
    0x000000000f190200  Thread-3

     Trace Formatted Data

    Time (UTC)          Thread ID          Tracepoint ID Type   Tracepoint Data
    08:58:35.527291919 *0x000000000f010500 j9trc.0       Event  Trace engine initialized for VM = 0x3ad4d0
    08:58:35.527349836  0x000000000f010500 j9prt.0       Event  Trace engine initialized for module j9port
    08:58:35.527354040  0x000000000f010500 j9thr.0       Event  Trace engine initialized for module j9thr
    08:58:35.529409621 *0x000000000f01eb00 j9trc.5       Event  Thread started VMthread = 0xf01eb00, name = (unnamed thread), nativeID = 0x24a798
    08:58:35.536134516  0x000000000f010500 j9vm.1        Entry >Create RAM class from ROM class 0x3cab680 in class loader 0x3042338
    08:58:35.536136384  0x000000000f010500 j9vm.80       Event  ROM class 0x3cab680 is named java/lang/Object
    08:58:35.536200373  0x000000000f010500 j9vm.2        Exit  <Created RAM class 0xf03ef00 from ROM class 0x3cab680