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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION | INSTALLATION | USAGE | FILES | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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PMDASTATSD(1) General Commands Manual PMDASTATSD(1)
pmdastatsd - StatsD protocol performance metric domain agent
(PMDA)
$PCP_PMDAS_DIR/statsd/pmdastatsd [-Z maximum udp packet size] [-P
port] [-v] [-g] [-o debug output filename] [-s] [-r parser type]
[-a port] [-z maximum of unprocessed packets]
StatsD is simple, text-based UDP protocol for receiving
monitoring data of applications in architecture client-server.
pmdastatsd is an Performance Metrics Domain Agent that collects
StatsD data, aggregates them and makes them available to any
Performance Co-Pilot client, which is ideal for easily tracking
stats in your application.
The statsd PMDA supports Counter, Gauge and Duration (with
instances for minimum, maximum, median, average, 90th percentile,
95th percentile, 99th percentile, count and standard deviation)
metric types, offers multiple parsing options: Ragel or
handwritten/custom parser, offers multiple aggregating options
for duration metric type: basic histogram or HDR histogram,
supports custom form of labels, logging, exports multiple metrics
about itself and may be configured either with an ini file or
command line options.
A brief description of the pmdastatsd command line options
follows:
-Z, --max-udp=<value>
Maximum allowed packet size, any larger then this will be
thrown away. Default: 1472
-P, --port=<value>
Which port agent will listen to for incoming traffic.
Default: 8125
-v, --verbose
Verbosity level. Prints info about agent execution into
logfile. Valid values are 0-2. 0 = Default value, shows
config information, read socket state, and first 100 dropped
messages. 1 = Shows PMNS and related information. 2 = Most
detailed verbosity level, also shows dropped messages above
100. All levels include those below.
-o, --debug-output-filename=<value>
You can send USR1 signal that 'asks' agent to output basic
information about all aggregated metric into a
$PCP_LOG_DIR/pmcd/statsd_{name} file. Default: 0
-s, --version
Flag controlling whether or not to log current agent version
on start. Default: 0
-p, --parser-type=<value>
Flag specifying which parser to use for incoming packets;
Basic = 0, Ragel = 1. Ragel parser includes better logging
when verbose = 2. Default: 0
-a, --duration-aggregation-type=<value>
Flag specifying which aggregation scheme to use for duration
metrics; basic histogram = 0, HDR histogram = 1. Default: 1
-z, -max-unprocessed-packets=<value>
Maximum size of packet queue that the agent will save in
memory. There are 2 queues: one for packets that are
waiting to be parsed and one for parsed packets before they
are aggregated. Default: 2048
The agent also looks for a pmdastatsd.ini file in the
$PCP_PMDAS_DIR/statsd directory. There, the same options may be
specified, albeit with slightly different names as follows:
max_udp_packet_size=<value>
port=<value>
verbose=<value>
debug=<value>
debug_output_filename=<value>
version=<value>
parser_type=<value>
duration_aggregation_type=<value>
max_unprocessed_packets=<value>
Should an option be specified in both pmdastatsd.ini and command
line, then the latter takes precedence. Most of the time you
will want to configure the agent with an ini file, as the agent
should never be executed directly.
Location of the log file. By default, a log file named
statsd.log is written in the current directory of pmcd(1) when
pmdastatsd is started, i.e. $PCP_LOG_DIR/pmcd. If the log file
cannot be created or is not writable, output is written to
standard error instead.
If you want to install the pmdastatsd, do the following as root:
# cd $PCP_PMDAS_DIR/statsd
# ./Install
To uninstall, do the following as root:
# cd $PCP_PMDAS_DIR/statsd
# ./Remove
pmdastatsd is launched by pmcd(1) and should never be executed
directly. The Install and Remove scripts notify pmcd(1) when the
agent is installed or removed.
Once started, pmdastatsd will listen on specified port for any
content in a form of:
<metricname>:<value>|<type>
There may be multiple such messages in single datagram, split by
a newline character, so this:
<metricname>:<value>|<type>\n<metricname>:<value>|<type>
is valid as well. Constraints for each of the above variables
are:
<metricname> = [a-z][a-zA-Z0-9_.]*
<value> = described further in each metric type subsection
<type> = One of the following: c , g or ms
If verbose logging is turned on, agent will log every message
parsed and related failures.
All recorded metrics will, if parsed and aggregated successfully,
be made available under statsd.* namespace.
1 Counter metric
Stores metrics as simple counters, adding any incoming values to
already existing ones.
<metricname>:<value>|c
Where value is positive number.
Example:
After aggregating following messages:
metric:20|c
metric:10|c
metric:3.3|c
Value available to PCP will be:
# pminfo --fetch statsd.metric
inst [0 or '/'] value 33.3
2 Gauge metric
Stores metrics as modifiable values, with an option to either
set, increment or decrement values.
<metricname>:<value>|g
Where value can be in a form of:
'-{value}', when negative value is supplied agent will
subtract value stored with the value passed
'+{value}', when positive value with a leading plus sign is
supplied, the agent will add the passed value to the value
stored
'{value}', when a value without any leading sign is supplied,
the agent will set the metric to the passed value.
Initial value for metric of gauge type is 0.
Example:
After aggregating following messages:
metric:20|g
metric:+10|g
metric:-3.3|g
Value available to PCP will be:
# pminfo --fetch statsd.metric
inst [0 or '/'] value 26.7
3 Duration metric
Aggregates values either via HDR histogram or simply stores all
values and then calculates instances from all values received.
<metricname>:<value>|ms
Where value is a positive number.
Example:
With larger message count, the values may vary based on selected
duration aggregation scheme.
After aggregating following messages:
metric:10|ms
metric:20|ms
Values available to PCP will be:
# pminfo --fetch statsd.metric
inst[0 or '/min'] value 10
inst[1 or '/max'] value 20
inst[2 or '/median'] value 10
inst[3 or '/average'] value 15
inst[4 or '/percentile90'] value 20
inst[5 or '/percentile95'] value 20
inst[6 or '/percentile99'] value 20
inst[7 or '/count'] value 2
inst[8 or '/std_deviation'] value 5
Note:
Once you send given metricname with specified type, the agent
will no longer aggregate any messages with same. metricname but
different type and will throw them away.
4 Labels
StatsD datagrams may also contain key:value pairs separated by
commas like so:
metric,tagX=X,tagW=W:5|c
OR
metric:5|ms|#tagX:X,tagW:W
Where tagX is a key, X is a value and tagW is a key, W is a
value.
Both key and value of such a pair are [a-ZA-Z0-9_.]{1,}.
Both formats are interchangeable and you may combine them
together. When key is not unique, right most value takes
precedence. This is valid:
metric,tagX=1:5|c|#tagX:2
Pair with key tagX will have value of 2.
You may use these labels to map specific values to some PCP
instances. PCP labels are also assigned to these PCP instances.
Pairs are ordered by key in resulting instance name and label
descriptor.
Single label:
metric,tagX=X:5|c
Such a payload would map to PCP as follows (non-related labels
were omitted):
# pminfo --fetch --labels statsd.metric
inst [0 or '/tagX=X'] value 5
inst [0 or '/tagX=X'] labels {'tagX':'X'}
As shown earlier you may also send payload with multiple labels.
When multiple labels are supplied they are split in instance name
by '::'. Example:
metric,tagX=X,tagW=W:5|c
This resolves to:
# pminfo --fetch --labels statsd.metric
inst [0 or '/tagX=X::tagW=W'] value 5
inst [0 or '/tagX=X::tagW=W'] labels {'tagX':'X','tagW':'W'}
Note:
Be mindful of the fact that duration metric type already maps to
instances even without any labels. Sending labeled value to such
a metric creates another 9 (as there are that many hardcoded)
instances.
Example:
metric:200|ms
metric:100|ms
metric,target=cpu2:10|ms
metric,target=cpu2:100|ms
metric,target=cpu2:1000|ms
Creates 18 instances. Duration data type and label name compose
instance name in following manner:
# pminfo --fetch --labels statsd.metric
...
inst [10 or '/max::target=cpu0'] value 1000
inst [10 or '/max::target=cpu0'] labels {'target':'cpu0'}
...
5 Hardcoded stats
Agent also exports metrics about itself:
statsd.pmda.received
Number of datagrams that the agent has received
statsd.pmda.parsed
Number of datagrams that were successfully parsed
statsd.pmda.dropped
Number of datagrams that were dropped
statsd.pmda.aggregated
Number of datagrams that were aggregated
statsd.pmda.metrics_tracked
This metric has 3 instances. counter - Number of tracked
counter metrics. gauge - Number of tracked gauge metrics.
duration - Number of tracked duration metrics. total -
Number of tracked metrics total.
statsd.pmda.time_spent_parsing
Total time in microseconds spent parsing metrics. Includes
time spent parsing a datagram and failing midway.
statsd.pmda.time_spent_aggregating
Total time in microseconds spent aggregating metrics.
Includes time spent aggregating a metric and failing midway.
statsd.pmda.settings.max_udp_packet_size
Maximum UDP packet size
statsd.pmda.settings.max_unprocessed_packets
Maximum size of unprocessed packets Q
statsd.pmda.settings.verbose
Verbosity flag
statsd.pmda.settings.debug_output_filename
Debug output filename
statsd.pmda.settings.port
Port that is listened to
statsd.pmda.settings.parser_type
Used parser type
statsd.pmda.settings.duration_aggregation_type
Used duration aggregation type
These names are blacklisted for user usage. No messages with
these names will processed. While not yet reserved, the whole
statsd.pmda.* namespace is not recommended to use for user
metrics.
$PCP_PMCDCONF_PATH
command line options used to launch pmdastatsd
$PCP_PMDAS_DIR/statsd/Install
installation script for the pmdastatsd agent
$PCP_PMDAS_DIR/statsd/Remove
undo installation script for the pmdastatsd agent
$PCP_LOG_DIR/pmcd/statsd.log
default log file for error messages and other information
from pmdastatsd
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).
PCPIntro(1), pmcd(1), pcp.conf(5) and pcp.env(5).
This page is part of the PCP (Performance Co-Pilot) project.
Information about the project can be found at
⟨http://www.pcp.io/⟩. If you have a bug report for this manual
page, send it to [email protected]. This page was obtained from the
project's upstream Git repository
⟨https://github.com/performancecopilot/pcp.git⟩ on 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-14.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
Performance Co-Pilot PCP PMDASTATSD(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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