Provided by: pcp_6.2.0-1.1build4_amd64 
NAME
pmie - inference engine for performance metrics
SYNOPSIS
pmie [-bCdeFfPqvVWxXz?] [-a archive] [-A align] [-c filename] [-h host] [-l logfile] [-m
note] [-j stompfile] [-n pmnsfile] [-o format] [-O offset] [-S starttime] [-t interval]
[-T endtime] [-U username] [-Z timezone] [filename ...]
DESCRIPTION
pmie accepts a collection of arithmetic, logical, and rule expressions to be evaluated at
specified frequencies. The base data for the expressions consists of performance metrics
values delivered in real-time from any host running the Performance Metrics Collection
Daemon (PMCD), or using historical data from Performance Co-Pilot (PCP) archives.
As well as computing arithmetic and logical values, pmie can execute actions (popup
alarms, write system log messages, and launch programs) in response to specified
conditions. Such actions are extremely useful in detecting, monitoring and correcting
performance related problems.
The expressions to be evaluated are read from configuration files specified by one or more
filename arguments. In the absence of any filename, expressions are read from standard
input.
Output from pmie is directed to standard output and standard error as follows:
stdout
Expression values printed in the verbose -v mode and the output of print actions.
stderr
Error and warning messages for any syntactic or semantic problems during expression
parsing, and any semantic or performance metrics availability problems during
expression evaluation.
OPTIONS
The available command line options are:
-a archive, --archive=archive
archive which is a comma-separated list of names, each of which may be the base name
of an archive or the name of a directory containing one or more archives written by
pmlogger(1). Multiple instances of the -a flag may appear on the command line to
specify a list of sets of archives. In this case, it is required that only one set
of archives be present for any one host. Also, any explicit host names occurring in
a pmie expression must match the host name recorded in one of the archive labels. In
the case of multiple sets of archives, timestamps recorded in the archives are used
to ensure temporal consistency.
-A align, --align=align
Force the initial time window to be aligned on the boundary of a natural time unit
align. Refer to PCPIntro(1) for a complete description of the syntax for align.
-b, --buffer
Output will be line buffered and standard output is attached to standard error. This
is most useful for background execution in conjunction with the -l option. The -b
option is always used for pmie instances launched from pmie_check(1).
-c config, --config=config
An alternative to specifying filename at the end of the command line.
-C, --check
Parse the configuration file(s) and exit before performing any evaluations. Any
errors in the configuration file are reported.
-d, --interact
Normally pmie would be launched as a non-interactive process to monitor and manage
the performance of one or more hosts. Given the -d flag however, execution is
interactive and the user is presented with a menu of options. Interactive mode is
useful mainly for debugging new expressions.
-e, --timestamp
When used with -V, -v or -W, this option forces timestamps to be reported with each
expression. The timestamps are in ctime(3) format, enclosed in parenthesis and
appear after the expression name and before the expression value, e.g.
expr_1 (Tue Feb 6 19:55:10 2001): 12
-f, --foreground
If the -l option is specified and there is no -a option (i.e. real-time monitoring)
then pmie is run as a daemon in the background (in all other cases foreground is the
default). The -f (and -F, see below) options force pmie to be run in the foreground,
independent of any other options.
-F, --systemd
Like -f, the -F option runs pmie in the foreground, but also does some housekeeping
(like create a pid file, change user id and notify systemd(1) when pmie has started
or is shutting down). This is intended for use when pmie is launched from systemd(1)
and the daemonizing has already been done. The -f and -F options are mutually
exclusive.
-h host, --host=host
By default performance data is fetched from the local host (in real-time mode) or the
host for the first named set of archives on the command line (in archive mode). The
host argument overrides this default. It does not override hosts explicitly named in
the expressions being evaluated. The host argument is interpreted as a connection
specification for pmNewContext, and is later mapped to the remote pmcd's self-
reported host name for reporting purposes. See also the %h vs. %c substitutions in
rule action strings below.
-j file
An alternative STOMP protocol configuration is loaded from stompfile. If this option
is not used, and the stomp action is used in any rule, the default location
$PCP_SYSCONF_DIR/pmie/config/stomp will be used.
-l logfile, --logfile=logfile
Standard error is sent to logfile.
-m note, --note=note
Used to indicate where pmie has been launched from, e.g. pmie_check(1) and
pmie_daily(1) use -m pmie_check and this is used by pmie to determine if it needs to
be restarted should the PMCD hostname change, as described in the HOSTNAME CHANGES
section below.
-n pmnsfile, --namespace=pmnsfile
An alternative Performance Metrics Name Space (PMNS) is loaded from the file
pmnsfile.
-o format, --format=format
When precessing performance data from an archive, the -o option may be used to
specify an alternate output format when a rule action is executed. See the
DIFFERENCES IN HOST AND ARCHIVE MODES section for a description of how the output
format may be constructed.
-O origin, --origin=origin
Specify the origin of the time window. See PCPIntro(1) for complete description of
this option.
-P, --primary
Identifies this as the primary pmie instance for a host. See the ``AUTOMATIC
RESTART'' section below for further details.
-q, --quiet
Suppresses diagnostic messages that would be printed to standard output by default,
especially the "evaluator exiting" message as this can confuse scripts.
-S starttime, --start=starttime
Specify the starttime of the time window. See PCPIntro(1) for complete description
of this option.
-t interval, --interval=interval
The interval argument follows the syntax described in PCPIntro(1), and in the
simplest form may be an unsigned integer (the implied units in this case are
seconds). The value is used to determine the sample interval for expressions that do
not explicitly set their sample interval using the pmie variable delta described
below. The default is 10.0 seconds.
-T endtime, --finish=endtime
Specify the endtime of the time window. See PCPIntro(1) for complete description of
this option.
-U username, --username=username
User account under which to run pmie. The default is the current user account for
interactive use. When run as a daemon, the unprivileged "pcp" account is used in
current versions of PCP, but in older versions the superuser account ("root") was
used by default.
-v Unless one of the verbose options -V, -v or -W appears on the command line,
expressions are evaluated silently, the only output is as a result of any actions
being executed. In the verbose mode, specified using the -v flag, the value of each
expression is printed as it is evaluated. The values are in canonical units; bytes
in the dimension of ``space'', seconds in the dimension of ``time'' and events in the
dimension of ``count''. See pmLookupDesc(3) for details of the supported dimension
and scaling mechanisms for performance metrics. The verbose mode is useful in
monitoring the value of given expressions, evaluating derived performance metrics,
passing these values on to other tools for further processing and in debugging new
expressions.
-V, --verbose
This option has the same effect as the -v option, except that the name of the host
and instance (if applicable) are printed as well as expression values.
-W This option has the same effect as the -V option described above, except that for
boolean expressions, only those names and values that make the expression true are
printed. These are the same names and values accessible to rule actions as the %h,
%i, %c and %v bindings, as described below.
-x, --secret-agent
Execute in domain agent mode. This mode is used within the Performance Co-Pilot
product to derive values for summary metrics, see pmdasummary(1). Only restricted
functionality is available in this mode (expressions with actions may not be used).
-X, --secret-applet
Run in secret applet mode (thin client).
-z, --hostzone
Change the reporting timezone to the timezone of the host that is the source of the
performance metrics, as identified via either the -h option or the first named set of
archives (as described above for the -a option).
-Z timezone, --timezone=timezone
Change the reporting timezone to timezone in the format of the environment variable
TZ as described in environ(7).
-?, --help
Display usage message and exit.
EXAMPLES
The following example expressions demonstrate some of the capabilities of the inference
engine.
The directory $PCP_DEMOS_DIR/pmie contains a number of other annotated examples of pmie
expressions.
The variable delta controls expression evaluation frequency. Specify that subsequent
expressions be evaluated once a second, until further notice:
delta = 1 sec;
If the total context switch rate exceeds 10000 per second per CPU, then display an alarm
notifier:
kernel.all.pswitch / hinv.ncpu > 10000 count/sec
-> alarm "high context switch rate %v";
If the high context switch rate is sustained for 10 consecutive samples, then launch
top(1) in an xterm(1) window to monitor processes, but do this at most once every 5
minutes:
all_sample (
kernel.all.pswitch @0..9 > 10 Kcount/sec * hinv.ncpu
) -> shell 5 min "xterm -e 'top'";
The following rules are evaluated once every 20 seconds:
delta = 20 sec;
If any disk is performing more than 60 I/Os per second, then print a message identifying
the busy disk to standard output and launch dkvis(1):
some_inst (
disk.dev.total > 60 count/sec
) -> print "busy disks:" " %i" &
shell 5 min "dkvis";
Refine the preceding rule to apply only between the hours of 9am and 5pm, and to require 3
of 4 consecutive samples to exceed the threshold before executing the action:
$hour >= 9 && $hour <= 17 &&
some_inst (
75 %_sample (
disk.dev.total @0..3 > 60 count/sec
)
) -> print "disks busy for 20 sec:" " [%h]%i";
The following two rules are evaluated once every 10 minutes:
delta = 10 min;
If either the / or the /usr filesystem is more than 95% full, display an alarm popup, but
not if it has already been displayed during the last 4 hours:
filesys.free #'/dev/root' /
filesys.capacity #'/dev/root' < 0.05
-> alarm 4 hour "root filesystem (almost) full";
filesys.free #'/dev/usr' /
filesys.capacity #'/dev/usr' < 0.05
-> alarm 4 hour "/usr filesystem (almost) full";
The following rule requires a machine that supports the lmsensors metrics. If the machine
environment temperature rises more than 2 degrees over a 10 minute interval, write an
entry in the system log:
lmsensors.coretemp_isa.temp1 @0 - lmsensors.coretemp_isa.temp1 @1 > 2
-> alarm "temperature rising fast" &
syslog "machine room temperature rise alarm";
And something interesting if you have performance problems with your Oracle database:
// back to 30sec evaluations
delta = 30 sec;
sid = "ptg1"; # $ORACLE_SID setting
lid = "223"; # latch ID from v$latch
lru = "#'$sid/$lid cache buffers lru chain'";
host = ":moomba.melbourne.sgi.com";
gets = "oracle.latch.gets $host $lru";
total = "oracle.latch.gets $host $lru +
oracle.latch.misses $host $lru +
oracle.latch.immisses $host $lru";
$total > 100 && $gets / $total < 0.2
-> alarm "high lru latch contention in database $sid";
The following ruleset will emit exactly one message depending on the availability and
value of the 1-minute load average.
delta = 1 minute;
ruleset
kernel.all.load #'1 minute' > 10 * hinv.ncpu ->
print "extreme load average %v"
else kernel.all.load #'1 minute' > 2 * hinv.ncpu ->
print "moderate load average %v"
unknown ->
print "load average unavailable"
otherwise ->
print "load average OK"
;
The following rule will emit a message when some filesystem is more than 75% full and is
filling at a rate that if sustained would fill the filesystem to 100% in less than 30
minutes.
some_inst (
100 * filesys.used / filesys.capacity > 75 &&
filesys.used + 30min * (rate filesys.used) > filesys.capacity
) -> print "filesystem will be full within 30 mins:" " %i";
If the metric mypmda.errors counts errors then the following rule will emit a message if
the rate of errors exceeds 1 per second provided the error count is less than 100.
mypmda.errors > 1 && instant mypmda.errors < 100
-> print "high error rate: %v";
QUICK START
The pmie specification language is powerful and large.
To expedite rapid development of pmie rules, the pmieconf(1) tool provides a facility for
generating a pmie configuration file from a set of generalized pmie rules. The supplied
set of rules covers a wide range of performance scenarios.
The Performance Co-Pilot User's and Administrator's Guide provides a detailed tutorial-
style chapter covering pmie.
EXPRESSION SYNTAX
This description is terse and informal. For a more comprehensive description see the
Performance Co-Pilot User's and Administrator's Guide.
A pmie specification is a sequence of semicolon terminated expressions.
Basic operators are modeled on the arithmetic, relational and Boolean operators of the C
programming language. Precedence rules are as expected, although the use of parentheses
is encouraged to enhance readability and remove ambiguity.
Operands are performance metric names (see PMNS(5)) and the normal literal constants.
Operands involving performance metrics may produce sets of values, as a result of
enumeration in the dimensions of hosts, instances and time. Special qualifiers may appear
after a performance metric name to define the enumeration in each dimension. For example,
kernel.percpu.cpu.user :foo :bar #cpu0 @0..2
defines 6 values corresponding to the time spent executing in user mode on CPU 0 on the
hosts ``foo'' and ``bar'' over the last 3 consecutive samples. The default interpretation
in the absence of : (host), # (instance) and @ (time) qualifiers is all instances at the
most recent sample time for the default source of PCP performance metrics.
Host and instance names that do not follow the rules for variables in programming
languages, i.e. alphabetic optionally followed by alphanumerics, should be enclosed in
single quotes.
Expression evaluation follows the law of ``least surprises''. Where performance metrics
have the semantics of a counter, pmie will automatically convert to a rate based upon
consecutive samples and the time interval between these samples. All numeric expressions
are evaluated in double precision, and where appropriate, automatically scaled into
canonical units of ``bytes'', ``seconds'' and ``counts''.
A rule is a special form of expression that specifies a condition or logical expression, a
special operator (->) and actions to be performed when the condition is found to be true.
The following table summarizes the basic pmie operators:
┌────────────────┬────────────────────────────────────────────────┐
│ Operators │ Explanation │
├────────────────┼────────────────────────────────────────────────┤
│+ - * / │ Arithmetic │
│< <= == >= > != │ Relational (value comparison) │
│! && || │ Boolean │
│-> │ Rule │
│rising │ Boolean, false to true transition │
│falling │ Boolean, true to false transition │
│rate │ Explicit rate conversion (rarely required) │
│instant │ No automatic rate conversion (rarely required) │
└────────────────┴────────────────────────────────────────────────┘
All operators are supported for numeric-valued operands and expressions. For string-
valued operands, namely literal string constants enclosed in double quotes or metrics with
a data type of string (PM_TYPE_STRING), only the operators == and != are supported.
The rate and instant operators are the logical inverse of one another, so an arithmetic
expression expr is equal to rate instant expr. The more useful cases involve using rate
with a metric that is not a counter to determine the rate of change over time or instant
with a metric that is a counter to determine if the current value is above or below some
threshold.
Aggregate operators may be used to aggregate or summarize along one dimension of a set-
valued expression. The following aggregate operators map from a logical expression to a
logical expression of lower dimension.
┌─────────────────────────┬─────────────┬──────────────────────────┐
│ Operators │ Type │ Explanation │
├─────────────────────────┼─────────────┼──────────────────────────┤
│some_inst │ Existential │ True if at least one set │
│some_host │ │ member is true in the │
│some_sample │ │ associated dimension │
├─────────────────────────┼─────────────┼──────────────────────────┤
│all_inst │ Universal │ True if all set members │
│all_host │ │ are true in the │
│all_sample │ │ associated dimension │
├─────────────────────────┼─────────────┼──────────────────────────┤
│N%_inst │ Percentile │ True if at least N │
│N%_host │ │ percent of set members │
│N%_sample │ │ are true in the │
│ │ │ associated dimension │
└─────────────────────────┴─────────────┴──────────────────────────┘
The following instantial operators may be used to filter or limit a set-valued logical
expression, based on regular expression matching of instance names. The logical
expression must be a set involving the dimension of instances, and the regular expression
is of the form used by egrep(1) or the Extended Regular Expressions of regcomp(3).
┌─────────────┬──────────────────────────────────────────┐
│ Operators │ Explanation │
├─────────────┼──────────────────────────────────────────┤
│match_inst │ For each value of the logical expression │
│ │ that is ``true'', the result is ``true'' │
│ │ if the associated instance name matches │
│ │ the regular expression. Otherwise the │
│ │ result is ``false''. │
├─────────────┼──────────────────────────────────────────┤
│nomatch_inst │ For each value of the logical expression │
│ │ that is ``true'', the result is ``true'' │
│ │ if the associated instance name does not │
│ │ match the regular expression. Otherwise │
│ │ the result is ``false''. │
└─────────────┴──────────────────────────────────────────┘
For example, the expression below will be ``true'' for disks attached to controllers 2 or
3 performing more than 20 operations per second:
match_inst "^dks[23]d" disk.dev.total > 20;
The following aggregate operators map from an arithmetic expression to an arithmetic
expression of lower dimension.
┌─────────────────────────┬───────────┬──────────────────────────┐
│ Operators │ Type │ Explanation │
├─────────────────────────┼───────────┼──────────────────────────┤
│min_inst │ Extrema │ Minimum value across all │
│min_host │ │ set members in the │
│min_sample │ │ associated dimension │
├─────────────────────────┼───────────┼──────────────────────────┤
│max_inst │ Extrema │ Maximum value across all │
│max_host │ │ set members in the │
│max_sample │ │ associated dimension │
├─────────────────────────┼───────────┼──────────────────────────┤
│sum_inst │ Aggregate │ Sum of values across all │
│sum_host │ │ set members in the │
│sum_sample │ │ associated dimension │
├─────────────────────────┼───────────┼──────────────────────────┤
│avg_inst │ Aggregate │ Average value across all │
│avg_host │ │ set members in the │
│avg_sample │ │ associated dimension │
└─────────────────────────┴───────────┴──────────────────────────┘
The aggregate operators count_inst, count_host and count_sample map from a logical
expression to an arithmetic expression of lower dimension by counting the number of set
members for which the expression is true in the associated dimension.
For action rules, the following actions are defined:
┌──────────┬────────────────────────────────────────┐
│Operators │ Explanation │
├──────────┼────────────────────────────────────────┤
│alarm │ Raise a visible alarm with xconfirm(1) │
│print │ Display on standard output │
│shell │ Execute with sh(1) │
│stomp │ Send a STOMP message to a JMS server │
│syslog │ Append a message to system log file │
└──────────┴────────────────────────────────────────┘
Multiple actions may be separated by the & and | operators to specify respectively
sequential execution (both actions are executed) and alternate execution (the second
action will only be executed if the execution of the first action returns a non-zero error
status.
Arguments to actions are an optional suppression time, and then one or more expressions (a
string is an expression in this context). Strings appearing as arguments to an action may
include the following special selectors that will be replaced at the time the action is
executed.
%h Host name(s) that make the left-most top-level expression in the condition true.
%c Connection specification string(s) or files for a PCP tool to reach the hosts or
archives that make the left-most top-level expression in the condition true.
%i Instance(s) that make the left-most top-level expression in the condition true.
%v One value from the left-most top-level expression in the condition for each host and
instance pair that makes the condition true.
Note that expansion of the special selectors is done by repeating the whole argument once
for each unique binding to any of the qualifying special selectors. For example if a rule
were true for the host mumble with instances grunt and snort, and for host fumble the
instance puff makes the rule true, then the action
...
-> shell myscript "Warning: %h:%i busy ";
will execute myscript with the argument string "Warning: mumble:grunt busy Warning:
mumble:snort busy Warning: fumble:puff busy".
By comparison, if the action
...
-> shell myscript "Warning! busy:" " %h:%i";
were executed under the same circumstances, then myscript would be executed with the
argument string "Warning! busy: mumble:grunt mumble:snort fumble:puff".
The semantics of the expansion of the special selectors leads to a common usage pattern in
an action, where one argument is a constant (contains no special selectors) the second
argument contains the desired special selectors with minimal separator characters, and an
optional third argument provides a constant postscript (e.g. to terminate any argument
quoting from the first argument). If necessary post-processing (e.g. in myscript) can
provide the necessary enumeration over each unique expansion of the string containing just
the special selectors.
For complex conditions, the bindings to these selectors is not obvious. It is strongly
recommended that pmie be used in the debugging mode (specify the -W command line option in
particular) during rule development.
BOOLEAN EXPRESSIONS
pmie expressions that have the semantics of a Boolean, e.g. foo.bar > 10 or some_inst (
my.table < 0 ) are assigned the values true or false or unknown. A value is unknown if
one or more of the underlying metric values is unavailable, e.g. pmcd(1) on the host
cannot be contacted, the metric is not in the PCP archive, no values are currently
available, insufficient values have been fetched to allow a rate converted value to be
computed or insufficient values have been fetched to instantiate the required number of
samples in the temporal domain.
Boolean operators follow the normal rules of Kleene logic (aka 3-valued logic) when
combining values that include unknown:
┌────────────┬───────────────────────────┐
│ │ B │
│ A and B ├─────────┬───────┬─────────┤
│ │ true │ false │ unknown │
├──┬─────────┼─────────┼───────┼─────────┤
│ │ true │ true │ false │ unknown │
│ ├─────────┼─────────┼───────┼─────────┤
│A │ false │ false │ false │ false │
│ ├─────────┼─────────┼───────┼─────────┤
│ │ unknown │ unknown │ false │ unknown │
└──┴─────────┴─────────┴───────┴─────────┘
┌────────────┬──────────────────────────┐
│ │ B │
│ A or B ├──────┬─────────┬─────────┤
│ │ true │ false │ unknown │
├──┬─────────┼──────┼─────────┼─────────┤
│ │ true │ true │ true │ true │
│ ├─────────┼──────┼─────────┼─────────┤
│A │ false │ true │ false │ unknown │
│ ├─────────┼──────┼─────────┼─────────┤
│ │ unknown │ true │ unknown │ unknown │
└──┴─────────┴──────┴─────────┴─────────┘
┌────────┬─────────┐
│ A │ not A │
├────────┼─────────┤
│ true │ false │
├────────┼─────────┤
│ false │ true │
├────────┼─────────┤
│unknown │ unknown │
└────────┴─────────┘
RULESETS
The ruleset clause is used to define a set of rules and actions that are evaluated in
order until some action is executed, at which point the remaining rules and actions are
skipped until the ruleset is again scheduled for evaluation. The keyword else is used to
separate rules. After one or more regular rules (with a predicate and an action), a
ruleset may include an optional
unknown -> action
clause, optionally followed by a
otherwise -> action
clause.
If all of the predicates in the rules evaluate to unknown and an unknown clause has been
specified then action associated with the unknown clause will be executed.
If no rule predicate is true and the unknown action is either not specified or not
executed and an otherwise clause has been specified, then the action associated with the
otherwise clause will be executed.
SCALE FACTORS
Scale factors may be appended to arithmetic expressions and force linear scaling of the
value to canonical units. Simple scale factors are constructed from the keywords:
nanosecond, nanosec, nsec, microsecond, microsec, usec, millisecond, millisec, msec,
second, sec, minute, min, hour, byte, Kbyte, Mbyte, Gbyte, Tbyte, count, Kcount and
Mcount, and the operator /, for example ``Kbytes / hour''.
MACROS
Macros are defined using expressions of the form:
name = constexpr;
Where name follows the normal rules for variables in programming languages, i.e.
alphabetic optionally followed by alphanumerics. constexpr must be a constant expression,
either a string (enclosed in double quotes) or an arithmetic expression optionally
followed by a scale factor.
Macros are expanded when their name, prefixed by a dollar ($) appears in an expression,
and macros may be nested within a constexpr string.
The following reserved macro names are understood.
minute Current minute of the hour.
hour Current hour of the day, in the range 0 to 23.
day Current day of the month, in the range 1 to 31.
month Current month of the year, in the range 0 (January) to 11 (December).
year Current year.
day_of_week
Current day of the week, in the range 0 (Sunday) to 6 (Saturday).
delta Sample interval in effect for this expression.
Dates and times are presented in the reporting time zone (see description of -Z and -z
command line options above).
AUTOMATIC RESTART
It is often useful for pmie processes to be started and stopped when the local host is
booted or shutdown, or when they have been detected as no longer running (when they have
unexpectedly exited for some reason). Refer to pmie_check(1) for details on automating
this process.
Optionally, each system running pmcd(1) may also be configured to run a ``primary'' pmie
instance. This pmie instance is launched by $PCP_RC_DIR/pmie, and is affected by the
files $PCP_SYSCONF_DIR/pmie/control, $PCP_SYSCONF_DIR/pmie/control.d (use chkconfig(8),
systemctl(1) or similar platform-specific commands to activate or disable the primary pmie
instance) and $PCP_VAR_DIR/config/pmie/config.default (the default initial configuration
file for the primary pmie).
The primary pmie instance is identified by the -P option. There may be at most one
``primary'' pmie instance on each system. The primary pmie instance (if any) must be
running on the same host as the pmcd(1) to which it connects (if any), so the -h and -P
options are mutually exclusive.
EVENT MONITORING
It is common for production systems to be monitored in a central location. Traditionally
on UNIX systems this has been performed by the system log facilities - see logger(1), and
syslogd(1). On Windows, communication with the system event log is handled by pcp-
eventlog(1).
pmie fits into this model when rules use the syslog action. Note that if the action
string begins with -p (priority) and/or -t (tag) then these are extracted from the string
and treated in the same way as in logger(1) and pcp-eventlog(1).
However, it is common to have other event monitoring frameworks also, into which you may
wish to incorporate performance events from pmie. You can often use the shell action to
send events to these frameworks, as they usually provide their a program for injecting
events into the framework from external sources.
A final option is use of the stomp (Streaming Text Oriented Messaging Protocol) action,
which allows pmie to connect to a central JMS (Java Messaging System) server and send
events to the PMIE topic. Tools can be written to extract these text messages and present
them to operations people (via desktop popup windows, etc). Use of the stomp action
requires a stomp configuration file to be setup, which specifies the location of the JMS
server host, port number, and username/password.
The format of this file is as follows:
host=messages.sgi.com # this is the JMS server (required)
port=61616 # and its listening here (required)
timeout=2 # seconds to wait for server (optional)
username=joe # (required)
password=j03ST0MP # (required)
topic=PMIE # JMS topic for pmie messages (optional)
The timeout value specifies the time (in seconds) that pmie should wait for
acknowledgements from the JMS server after sending a message (as required by the STOMP
protocol). Note that on startup, pmie will wait indefinitely for a connection, and will
not begin rule evaluation until that initial connection has been established. Should the
connection to the JMS server be lost at any time while pmie is running, pmie will attempt
to reconnect on each subsequent truthful evaluation of a rule with a stomp action, but not
more than once per minute. This is to avoid contributing to network congestion. In this
situation, where the STOMP connection to the JMS server has been severed, the stomp action
will return a non-zero error value.
DIFFERENCES IN HOST AND ARCHIVE MODES
When running in host mode, the delta interval for each rule determines a real-time delay
between rule evaluation, so pmie spends most if its time sleeping and waiting for the next
scheduled rule evaluation.
When running in archive mode, pmie uses the delta interval for each rule to determine how
frequently the rules are evaluated against the archive data, but unlike host mode there
are no real-time delays as the archive is ``replayed'' as fast as possible.
In archive mode when a rule predicate evaluates true then the action is modified, so that
rather than posting to syslog or raising a visible alarm or running a shell command or
sending a stomp message, pmie prints the name of the action, the timestamp from the
archive when the rule predicate triggering the action was true and all of the arguments
that would have been passed to the real action in host mode.
For example, given the rule:
delta = 10 sec;
kernel.all.nprocs > 10 * hinv.ncpu -> print "lotsaprocs:" " %v";
when run against an archive, the output appears as:
print Mon Sep 4 00:10:21 2017: lotsaprocs: 1292
print Mon Sep 4 00:10:31 2017: lotsaprocs: 1294
print Mon Sep 4 00:10:41 2017: lotsaprocs: 1291
...
The rationale is that the context in which the action would have been executed (in host
mode) was at a time in the past and the possibly on a different host (if the archive was
collected from one host, but pmie is being run on a different host). So flooding syslog
with misleading messages or an avalanche visual alarms or a lot of STOMP messages or a
shell command that might not even work on the host where pmie is being run, are all
examples of ``badness'' to be avoided. Rather the output is text in a regular format
suitable for post-processing with a range of filters and performance analysis tools.
The output format can be changed using the -o option which consists of literal characters
with the following embedded ``meta-field'' tokens:
%a The name of the action, e.g. print, syslog, etc.
%d The date and time in ctime(3) format when the action would have been executed.
%f The name of the configuration file containing the action being executed, else <stdin>
if the rules were read from standard input.
%l The (approximate) line number in the configuration file for the action being executed.
%m The message component of the action.
%u The date and time when the action would have been executed in extended ctime(3) format
with microsecond precision for the time.
%% A literal percent character.
The default output format is equivalent to a format of %a %d: %m.
SIGNALS
If pmie is sent a SIGHUP signal, the logfile will be closed, unlinked and re-opened. This
is used by pmie_daily(1) to achieve nightly log rotation.
Most of the time pmie is sleeping, waiting until the next set of rules needs to be
evaluated. Sending pmie a SIGUSR1 signal will cause the details for the next set of rules
to be dumped on logfile, including how long the current sleep is and how much time
remains. The scheduling of rules is not changed by this action.
HOSTNAME CHANGES
The hostname of the PMCD that is providing metrics to pmie is used in several ways.
PMCD's hostname is user internally to provide a value for the %h substitutions in rule
action strings.
For pmie instances using a local PMCD that are launched and managed by pmie_check(1) and
pmie_daily(1), (or the systemd(1) or cron(8) services that use these scripts), the local
hostname may also be used to construct the name of a directory where the pmie logs for one
host are stored, e.g. $PCP_LOG_DIR/pmie/<hostname>.
The hostname of the PMCD host may change during boot time when the system transitions from
a temporary hostname to a persistent hostname, or by explicit administrative action
anytime after the system has been booted. When this happens, pmie may need to take
special action, specifically if the pmie instance was launched from pmie_check(1) or
pmie_daily(1), then pmie must exit. Under normal circumstances systemd(1) or cron(8) will
launch a new pmie shortly thereafter, and this new pmie instance will be operating in the
context of the new hostname for the host where PMCD is running.
BUGS
The lexical scanner and parser will attempt to recover after an error in the input
expressions. Parsing resumes after skipping input up to the next semi-colon (;), however
during this skipping process the scanner is ignorant of comments and strings, so an
embedded semi-colon may cause parsing to resume at an unexpected place. This behavior is
largely benign, as until the initial syntax error is corrected, pmie will not attempt any
expression evaluation.
FILES
$PCP_DEMOS_DIR/pmie/*
annotated example rules
$PCP_VAR_DIR/pmns/*
default PMNS specification files
$PCP_TMP_DIR/pmie
pmie maintains files in this directory to identify the running pmie instances and to
export runtime information about each instance - this data forms the basis of the
pmcd.pmie performance metrics
$PCP_PMIECONTROL_PATH
the default set of pmie instances to start at boot time - refer to pmie_check(1) for
details
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).
When executing shell actions, pmie overrides two variables - IFS and PATH - in the
environment of the child process. IFS is set to "\t\n". The PATH is set to a combination
of a default path for all platforms ("/usr/sbin:/sbin:/usr/bin:/bin") and several
configurable components. These are (in this order): $PCP_BIN_DIR, $PCP_BINADM_DIR and
$PCP_PLATFORM_PATHS.
When executing popup alarm actions, pmie will use the value of $PCP_XCONFIRM_PROG as the
visual notification program to run. This is typically set to pmconfirm(1), a cross-
platform dialog box.
UNIX SEE ALSO
logger(1).
WINDOWS SEE ALSO
pcp-eventlog(1).
SEE ALSO
PCPIntro(1), pmcd(1), pmconfirm(1), pmdumplog(1), pmie_check(1), pmieconf(1),
pmie_daily(1), pminfo(1), pmlogger(1), pmval(1), systemd(1), ctime(3), PMAPI(3),
pcp.conf(5), pcp.env(5) and PMNS(5).
USER GUIDE
For a more complete description of the pmie language, refer to the Performance Co-Pilot
Users and Administrators Guide. This is available online from:
https://pcp.readthedocs.io/en/latest/UAG/PerformanceMetricsInferenceEngine.html