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Use trace with IBM MQ server on IBM i

Use the TRCMQM command to start and stop tracing and specify the type of trace that you require.

There are two stages in using trace:
  1. Decide whether we want early tracing. Early tracing lets you trace the creation and startup of queue managers. Note, however, that early trace can easily generate large amounts of trace, because it is implemented by tracing all jobs for all queue managers. To enable early tracing, use TRCMQM with the TRCEARLY parameter set to *YES.
  2. Start tracing work using TRCMQM *ON. To stop the trace, you have two options:

    • TRCMQM *OFF, to stop collecting trace records for a queue manager. The trace records are written to files in the /QIBM/UserData/mqm/trace directory.
    • TRCMQM *END, to stop collecting trace records for all queue managers and to disable early trace. This option ignores the value of the TRCEARLY parameter.

Specify the level of detail we want, using the TRCLEVEL parameter set to one of the following values:

    *DFT
    For minimum-detail level for flow processing trace points.

    *DETAIL
    For high-detail level for flow processing trace points.

    *PARMS
    For default-detail level for flow processing trace points.

Specify the type of trace output we want, using the OUTPUT parameter set to one of the following values:

    *MQM
    Collect binary IBM MQ trace output in the directory specified by the TRCDIR parameter. This value is the default value.

    *MQMFMT
    Collect formatted IBM MQ trace output in the directory specified by the TRCDIR parameter.

    *PEX
    Collect Performance Explorer (PEX) trace output

    *ALL
    Collect both IBM MQ unformatted trace and PEX trace output


Selective trace

We can reduce the amount of trace data being saved, improving runtime performance, using the command TRCMQM with F4=prompt, then F9 to customize the TRCTYPE and EXCLUDE parameters:

    TRCTYPE
    Specifies the type of trace data to store in the trace file. If we omit this parameter, all trace points except those trace points specified in EXCLUDE are enabled.

    EXCLUDE
    Specifies the type of trace data to omit from the trace file. If we omit this parameter, all trace points specified in TRCTYPE are enabled.

The options available on both TRCTYPE and EXCLUDE are:

    *ALL (TRCTYPE only)
    All the trace data as specified by the following keywords is stored in the trace file.

    trace-type-list
    We can specify more than one option from the following keywords, but each option can occur only once.

    *API
    Output data for trace points associated with the MQI and major queue manager components.

    *CMTRY
    Output data for trace points associated with comments in the IBM MQ components.

    *COMMS
    Output data for trace points associated with data flowing over communications networks.

    *CSDATA
    Output data for trace points associated with internal data buffers in common services.

    *CSFLOW
    Output data for trace points associated with processing flow in common services.

    *LQMDATA
    Output data for trace points associated with internal data buffers in the local queue manager.

    *LQMFLOW
    Output data for trace points associated with processing flow in the local queue manager.

    *OTHDATA
    Output data for trace points associated with internal data buffers in other components.

    *OTHFLOW
    Output data for trace points associated with processing flow in other components.

    *RMTDATA
    Output data for trace points associated with internal data buffers in the communications component.

    *RMTFLOW
    Output data for trace points associated with processing flow in the communications component.

    *SVCDATA
    Output data for trace points associated with internal data buffers in the service component.

    *SVCFLOW
    Output data for trace points associated with processing flow in the service component.

    *VSNDATA
    Output data for trace points associated with the version of IBM MQ running.


Wrapping trace

Use the MAXSTG parameter to wrap trace, and to specify the maximum size of storage to be used for the collected trace records. The options are:

    *DFT
    Trace wrapping is not enabled. For each job, trace data is written to a file with the suffix .TRC until tracing is stopped.

    maximum-K-bytes
    Trace wrapping is enabled. When the trace file reaches its maximum size, it is renamed with the suffix .TRS, and a new trace file with suffix .TRC is opened. Any existing .TRS file is deleted. Specify a value in the range 1 through 16 000.


Formatting trace output

To format any trace output:

  • Enter the QShell
  • Enter the command 
    /QSYS.LIB/QMQM.LIB/DSPMQTRC.PGM [-t Format] [-h] [-s]
[-o OutputFileName] InputFileName

    where:

      InputFileName
      Is a required parameter specifying the name of the file containing the unformatted trace. For example /QIBM/UserData/mqm/trace/AMQ12345.TRC.

      -t FormatTemplate
      Specifies the name of the template file containing details of how to display the trace. The default value is /QIBM/ProdData/mqm/lib/amqtrc.fmt.

      -h
      Omit header information from the report.

      -s
      Extract trace header and put to stdout.

      -o output_filename
      The name of the file into which to write formatted data.

We can also specify dspmqtrc * to format all trace.

Parent topic: Use trace


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Last updated: 2020-10-04