Provided by: pcp_3.8.12ubuntu1_amd64 bug

NAME

       dbpmda - debugger for Performance Co-Pilot PMDAs

SYNOPSIS

       dbpmda [-ei] [-n pmnsfile] [-q timeout] [-U username]

DESCRIPTION

       dbpmda is an interactive interface to the interactions between a Performance Metric Domain
       Agent (PMDA(3)) and the Performance Metric Collector Daemon (pmcd(1)).  This allows  PMDAs
       to be attached, initialized and exercised to test for correctness.

       dbpmda  interactively  prompts  the  user for commands, many of which emulate the Protocol
       Data Units (PDUs) that may be sent by a pmcd(1) process.  After running dbpmda, enter  the
       command  help  to  get  a  list  of  the  available  commands.   The example section below
       illustrates a session using dbpmda to test a PMDA.

       To simplify repetitive testing of a PMDA,  the  file  .dbpmdarc  in  the  current  working
       directory  can  contain  a  list  of  commands that will be executed by dbpmda on startup,
       before the user is prompted to enter further commands interactively.  While processing the
       .dbpmdarc file, interactive mode and command echoing are enabled and then reset at the end
       of the .dbpmdarc file (see the -i and -e command line arguments below).

       If the system supports readline(3) then this will be used to read commands when  input  is
       from a tty device, so history and command line editing are available.

       dbpmda accepts the following command line arguments:

       -e     Echo the input to stdout.  This is useful when the input is redirected from a file.

       -i     Emulate interactive behavior and prompt for new commands, even if standard input is
              not a tty device.

       -n pmnsfile
              Normally dbpmda operates on the distributed Performance Metrics Name Space  (PMNS),
              however  if the -n option is specified an alternative local PMNS is loaded from the
              file pmnsfile.

       -q timeout
              The pmcd to agent version exchange protocol (new in PCP 2.0 - introduced to provide
              backward  compatibility)  uses  this timeout to specify how long dbpmda should wait
              before assuming that no version response is coming from an agent.  If this  timeout
              is  reached,  the agent is assumed to be an agent which does not understand the PCP
              2.0 protocol.  The default timeout interval is five  seconds,  but  the  -q  option
              allows  an  alternative  timeout  interval  (which must be greater than zero) to be
              specified.  The unit of time is seconds.

       -U username
              User account under which to run dbpmda.

       As there are no timeout constraints on a PMDA while using dbpmda (as compared to pmcd(1)),
       another  debugger like gdb(1) can be used on the PMDA process once it has been attached to
       dbpmda.

EXAMPLE

       Below is a dbpmda session using the simple PMDA. A .dbpmdarc  file  is  used  to  set  the
       debugging flag, open the PMDA and display the current status of the debugger:

            $ cat .dbpmdarc
            debug libpmda
            open dso pmda_simple.so simple_init 253
            status

       When dbpmda is run, the commands in the .dbpmdarc file are executed first:

            $ dbpmda
            .dbpmdarc> debug libpmda
            .dbpmdarc> open dso pmda_simple.so simple_init 253
            [Fri Sep 19 10:19:55] dbpmda(11651) Debug: pmdaInit: PMDA simple DSO: Metric 0.0.1(1) matched to indom 253.0(0)
            [Fri Sep 19 10:19:55] dbpmda(11651) Debug: pmdaInit: PMDA simple DSO: help file $PCP_PMDAS_DIR/simple/help opened
            [Fri Sep 19 10:19:55] dbpmda(11651) Info: name        = simple DSO
            [Fri Sep 19 10:19:55] dbpmda(11651) Info: domain      = 253
            [Fri Sep 19 10:19:55] dbpmda(11651) Info: num metrics = 4
            [Fri Sep 19 10:19:55] dbpmda(11651) Info: num indom   = 1
            [Fri Sep 19 10:19:55] dbpmda(11651) Info: direct map  = 1
            .dbpmdarc> status

            Namespace:              (default)
            PMDA:                   ./pmda_simple.so
            Connection:             dso
            DSO Interface Version:  2
            PMDA PMAPI Version:     2
            pmDebug:                32768 ( libpmda )
            Timer:                  off
            Getdesc:                off

            Dump Instance Profile state=INCLUDE, 0 profiles

            .dbpmdarc>

       To  examine  the  metric  and  instance descriptors, the desc and instance commands can be
       used.  Metrics may be identified either by name,  or  using  the  ``dotted''  notation  to
       specify  the  domain,  cluster  and  item  fields  of  a  PMID.   Instance domains must be
       identified using a ``dotted'' notation to specify the domain and serial fields. The syntax
       for most commands will be displayed if the command is given without any arguments:

            dbpmda> desc 253.0.0
            PMID: 253.0.0
                Data Type: 32-bit unsigned int  InDom: PM_INDOM_NULL 0xffffffff
                Semantics: instant  Units: none
            dbpmda> instance
            instance indom# [ number | name | "name" ]
            dbpmda> instance 253.0
            pmInDom: 253.0
            [  0] inst: 0 name: "red"
            [  1] inst: 1 name: "green"
            [  2] inst: 2 name: "blue"

       To test the most important component of a PMDA, the fetch, it is often useful to determine
       the time it takes the PMDA to respond.  The timer may be turned on before giving a fetch:

            dbpmda> timer on
            dbpmda> fetch simple.numfetch 253.0.1
            PMID(s): 253.0.0 253.0.1
            pmResult dump from 0x100078e0 timestamp: 0.000000 11:00:00.000 numpmid: 2
              253.0.0 (simple.numfetch): numval: 1 valfmt: 0 vlist[]:
               value 1 1.4012985e-45 0x1
              253.0.1 (simple.color): numval: 3 valfmt: 0 vlist[]:
                inst [0 or ???] value 1 1 1.4012985e-45 0x1
                inst [1 or ???] value 101 1.4153114e-43 0x65
                inst [2 or ???] value 201 2.8166099e-43 0xc9
            Timer: 0.003921 seconds
            dbpmda> timer off

       The integer, floating point and hex translations of the values in the  pmResult  structure
       are  dumped if getdesc is set to off (the default).  Setting getdesc to on would result in
       only integer values being dumped in the  above  fetch  as  the  descriptor  describes  the
       metrics of 32-bit unsigned integers.

       The  simple  PMDA  also  supports  the store operation which can be tested with subsequent
       fetch commands:

            dbpmda> store simple.numfetch "42"
            PMID: 253.0.0
            Getting description...
            Getting Result Structure...
            253.0.0: 2 -> 42
            dbpmda> fetch simple.numfetch
            PMID(s): 253.0.0
            pmResult dump from 0x100078e0 timestamp: 0.000000 11:00:00.000 numpmid: 1
              253.0.0 (simple.numfetch): numval: 1 valfmt: 0 vlist[]:
               value 43

       A profile can be specified for each  instance  domain  which  includes  all,  some  or  no
       instances:

            dbpmda> help profile

            profile indom# [ all | none ]
            profile indom# [ add | delete ] number

            For the instance domain specified, the profile may be changed to
            include 'all' instances, no instances, add an instance or delete
            an instance.

            dbpmda> profile 253.0 none
            dbpmda> getdesc on
            dbpmda> fetch 253.0.1
            PMID(s): 253.0.1
            pmResult dump from 0x100078e0 timestamp: 0.000000 11:00:00.000 numpmid: 1
              253.0.1 (simple.color): No values returned!
            dbpmda> profile 253.0 add 2
            dbpmda> fetch 253.0.1
            PMID(s): 253.0.1
            pmResult dump from 0x100078e0 timestamp: 0.000000 11:00:00.000 numpmid: 1
              253.0.1 (simple.color): numval: 1 valfmt: 0 vlist[]:
               value 202
            dbpmda> profile 253.0 add 0
            dbpmda> fetch 253.0.1
            PMID(s): 253.0.1
            pmResult dump from 0x100078e0 timestamp: 0.000000 11:00:00.000 numpmid: 1
              253.0.1 (simple.color): numval: 2 valfmt: 0 vlist[]:
                inst [0 or ???] value 2
                inst [2 or ???] value 203
            dbpmda> status

            PMDA       = pmda_simple.so
            Connection = dso
            pmDebug    = 32768 ( libpmda )
            Timer      = off

            Dump Instance Profile state=INCLUDE, 1 profiles
                    Profile [0] indom=1061158913 [253.0] state=EXCLUDE 2 instances
                            Instances: [2] [0]
            dbpmda> quit

       The  watch command (usage: watch filename ) opens an xwsh window which tails the specified
       log file.  This window must be closed by the user when no longer required.

       The wait command is equivalent to sleep (1) and takes a single integer argument.

       The introduction of dynamic subtrees in the PMNS and PMDA_INTERFACE_4 in  libpcp_pmda  has
       led  to  additional  commands being supported in dbpmda to exercise the associated dynamic
       PMNS services.  The examples below are based on the sample PMDA.

            $ dbpmda
            dbpmda> open pipe /var/lib/pcp/pmdas/sample/pmdasample -d 29
            dbpmda> Start pmdasample PMDA: /var/lib/pcp/pmdas/sample/pmdasample -d 29
            dbpmda> children sample.secret
            Metric: sample.secret
               non-leaf foo
                   leaf bar
            dbpmda> traverse sample.secret.foo
            Metric: sample.secret.foo
               sample.secret.foo.bar.max.redirect
               sample.secret.foo.one
               sample.secret.foo.two
               sample.secret.foo.bar.three
               sample.secret.foo.bar.four
               sample.secret.foo.bar.grunt.five
               sample.secret.foo.bar.grunt.snort.six
               sample.secret.foo.bar.grunt.snort.huff.puff.seven
            dbpmda> pmid sample.secret.foo.bar.four
            Metric: sample.secret.foo.bar.four
               29.0.1004
            dbpmda> name 29.0.1006
            PMID: 29.0.1006
               sample.secret.foo.bar.grunt.snort.six

       The children command returns the next name component for all the direct descendants  of  a
       node  within a dynamic subtree of the PMNS.  The related traverse command returns the full
       metric names for all leaf nodes in the PMNS below the specified non-leaf node in a dynamic
       subtree of the PMNS.

       The  name  and  pmid  commands exercise the translation of metric names to PMIDs (and vice
       versa) for metrics within a dynamic subtree of the PMNS.

       If the commands children, traverse, pmid or name are used with a PMDA that  is  not  using
       PMDA_INTERFACE_4  or  with performance metric names that are not part of a dynamic subtree
       of the PMNS, then the PMDA would be expected to return errors (PM_ERR_NAME or PM_ERR_PMID)
       to  reflect the fact that the operation is in error (outside a dynamic subtree of the PMNS
       it is pmcd(1) and not the PMDA that is responsible for implementing these functions).

       Client authentication mechanisms have been incorporated into the PMCS, providing  per-user
       (and   per-connection)   information   that   is   available   to  PMDAs.   A  PMDA  using
       PMDA_INTERFACE_6 or later in libpcp_pmda is able to make use of the "attribute" method  to
       gain visibility into these authenticated connections, with access to information including
       user and group identifiers, user name, and so on.  The need to  exercise  and  debug  this
       interface  has  led to a new dbpmda command.  The following example is based on the sample
       PMDA.

            $ dbpmda
            dbpmda> open pipe pmdasample -D AUTH -l logfile
            dbpmda> Start pmdasample PMDA: pmdasample -D AUTH -l logfile
            dbpmda> attr "username" "tanya"
            Attribute: username=tanya
            Success
            dbpmda> attr 11 "0"
            Attribute: userid=0
            Success
            dbpmda>

       The attr command passes connection attributes (PCP_ATTR keys) and their values into a PMDA
       in  much  the  same  way  that PMCD would for a client connection.  dbpmda always passes a
       client context identifier of zero, and while no validity checking on values  is  performed
       only recognised attributes can be set.

       In  the  example  above  the  AUTH  debug flag is set for the PMDA, which uses this in its
       attribute callback and records each attribute and value pair sent to it in its logfile.

       Note that authentication checks have already been performed by PMCD by the time a PMDA  is
       presented with these attributes, so no further verification is necessary by the PMDA.

CAVEATS

       A value cannot be stored into metrics of type PM_TYPE_AGGREGATE or PM_TYPE_EVENT.

       dbpmda  uses  fork(2)  and  exec(2) to attach to daemon PMDAs.  dbpmda makes no attempt to
       detect the termination of the daemon PMDA process, so it is possible for a  PMDA  to  exit
       unexpectedly  without  any  notification. However, any further communication attempts with
       the PMDA will result in errors which will indicate that the PMDA is no longer responding.

FILES

       ./.dbpmdarc
                 List of commands to do on startup.

PCP ENVIRONMENT

       Environment variables with the prefix PCP_ are used to parameterize the file and directory
       names used by PCP.  On each installation, the file /etc/pcp.conf contains the local values
       for these variables.  The $PCP_CONF  variable  may  be  used  to  specify  an  alternative
       configuration file, as described in pcp.conf(5).

SEE ALSO

       gdb(1),   pmcd(1),   pmdbg(1),   exec(2),  fork(2),  PMAPI(3),  PMDA(3),  pcp.conf(5)  and
       pcp.env(5).