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Statsite

This is a stats aggregation server. Statsite is based heavily on Etsy's StatsD https://github.com/etsy/statsd. This is a re-implementation of the Python version of statsite https://github.com/kiip/statsite.

Features

  • Basic key/value metrics
  • Send timer data, statsite will calculate:
    • Mean
    • Min/Max
    • Standard deviation
    • Median, Percentile 95, Percentile 99
  • Send counters that statsite will aggregate

Architecture

Statsite is designed to be both highly performant, and very flexible. To achieve this, it implements the stats collection and aggregation in pure C, using libev to be extremely fast. This allows it to handle hundreds of connections, and millions of metrics. After each flush interval expires, statsite performs a fork/exec to start a new stream handler invoking a specified application. Statsite then streams the aggregated metrics over stdin to the application, which is free to handle the metrics as it sees fit.

This allows statsite to aggregate metrics and then ship metrics to any number of sinks (Graphite, SQL databases, etc). There is an included Python script that ships metrics to graphite.

Additionally, statsite tries to minimize memory usage by not storing all the metrics that are received. Counter values are aggregated as they are received, and timer values are stored and aggregated using the Cormode-Muthurkrishnan algorithm from "Effective Computation of Biased Quantiles over Data Streams". This means that the percentile values are not perfectly accurate, and are subject to a specifiable error epsilon. This allows us to store only a fraction of the samples.

Install

Download and build from source::

$ git clone https://armon@github.com/armon/statsite.git
$ cd statsite
$ pip install SCons  # Uses the Scons build system, may not be necessary
$ scons
$ ./statsite

Building the test code may generate errors if libcheck is not available. To build the test code successfully, do the following::

$ cd deps/check-0.9.8/
$ ./configure
$ make
# make install
# ldconfig (necessary on some Linux distros)
$ cd ../../
$ scons test_runner

At this point, the test code should build successfully.

Usage

Statsite is configured using a simple INI file. Here is an example configuration file::

[statsite]
port = 8125
udp_port = 8125
log_level = INFO
flush_interval = 10
timer_eps = 0.01
stream_cmd = python sinks/graphite.py localhost 2003

Then run statsite, pointing it to that file::

statsite -f /etc/statsite.conf

Protocol

By default, Statsite will listen for TCP and UDP connections. A message looks like the following (where the flag is optional)::

key:value|type[|@flag]

Messages must be terminated by newlines (\n).

Currently supported message types:

  • kv - Simple Key/Value.
  • ms - Timer.
  • c - Counter.

After the flush interval, the counters and timers of the same key are aggregated and this is sent to the store.

Examples:

The following is a simple key/value pair, in this case reporting how many queries we've seen in the last second on MySQL::

mysql.queries:1381|kv

The following is a timer, timing the response speed of an API call::

api.session_created:114|ms

The next example is increments the "rewards" counter by 1::

rewards:1|c

And this example decrements the "inventory" counter by 7::

inventory:-7|c

Writing Statsite Sinks

Statsite only ships with a graphite sink by default, but any executable can be used as a sink. The sink should read its inputs from stdin, where each metric is in the form::

key|val|timestamp

Each metric is separated by a newline. The process should terminate with an exit code of 0 to indicate success.

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