go-carbon

Golang implementation of Graphite/Carbon server with classic architecture: Agent -> Cache -> Persister

Features

• Receive metrics from TCP and UDP (plaintext protocol)
• Receive metrics with Pickle protocol (TCP only)
• storage-schemas.conf
• storage-aggregation.conf
• Carbonlink (requests to cache from graphite-web)
• Logging with rotation (reopen log by HUP signal or inotify event)
• Many persister workers (using many cpu cores)
• Run as daemon
• Grace stop on USR2 signal: close all socket listeners, flush cache to disk and stop carbon
• Reload persister config (whisper section of main config, storage-schemas.conf and storage-aggregation.conf) on HUP signal

Performance

Faster than default carbon. In all conditions :) How much faster depends on server hardware, storage-schemas, etc.

The result of replacing "carbon" to "go-carbon" on a server with a load up to 900 thousand metric per minute:

Installation

Use binary packages from releases page or build manually:

# build binary
git clone https://github.com/lomik/go-carbon.git
cd go-carbon
make submodules
make

# build rpm (centos 6)
make rpm

# build debian/ubuntu package
make deb

Install debian dependencies: 
apt-get install golang 

# hand-made install
sudo install -m 0755 go-carbon /usr/local/bin/go-carbon
sudo go-carbon --config-print-default > /usr/local/etc/carbon.conf
sudo vim /usr/local/etc/carbon.conf
sudo go-carbon --config /usr/local/etc/carbon.conf --daemon

Configuration

$ go-carbon --help
Usage of go-carbon:
  -check-config=false: Check config and exit
  -config="": Filename of config
  -config-print-default=false: Print default config
  -daemon=false: Run in background
  -pidfile="": Pidfile path (only for daemon)
  -version=false: Print version

[common]
# Run as user. Works only in daemon mode
user = ""
# If logfile is empty use stderr
logfile = "/var/log/go-carbon/go-carbon.log"
# Logging error level. Valid values: "debug", "info", "warn", "warning", "error"
log-level = "info"
# Prefix for store all internal go-carbon graphs. Supported macroses: {host}
graph-prefix = "carbon.agents.{host}."
# Interval of storing internal metrics. Like CARBON_METRIC_INTERVAL
metric-interval = "1m0s"
# Increase for configuration with multi persisters
max-cpu = 1

[whisper]
data-dir = "/data/graphite/whisper/"
# http://graphite.readthedocs.org/en/latest/config-carbon.html#storage-schemas-conf. Required
schemas-file = "/data/graphite/schemas"
# http://graphite.readthedocs.org/en/latest/config-carbon.html#storage-aggregation-conf. Optional
aggregation-file = ""
# Workers count. Metrics sharded by "crc32(metricName) % workers"
workers = 1
# Limits the number of whisper update_many() calls per second. 0 - no limit
max-updates-per-second = 0
# Sparse file creation
sparse-create = false
enabled = true

[cache]
# Limit of in-memory stored points (not metrics)
max-size = 1000000
# Capacity of queue between receivers and cache
input-buffer = 51200
# Strategy to persist metrics. Values: "max","sorted","noop"
#   "max" - write metrics with most unwritten datapoints first
#   "sorted" - sort by timestamp of first unwritten datapoint.
#   "noop" - pick metrics to write in unspecified order,
#            requires least CPU and improves cache responsiveness
write-strategy = "max"

[udp]
listen = ":2003"
enabled = true
# Enable optional logging of incomplete messages (chunked by MTU)
log-incomplete = false

[tcp]
listen = ":2003"
enabled = true

[pickle]
listen = ":2004"
enabled = true
# Limit message size for prevent memory overflow
max-message-size = 67108864

[carbonlink]
listen = "127.0.0.1:7002"
enabled = true
# Close inactive connections after "read-timeout"
read-timeout = "30s"
# Return empty result if cache not reply
query-timeout = "100ms"

[pprof]
listen = "localhost:7007"
enabled = false

OS tuning

It is crucial for performance to ensure that your OS tuned so that go-carbon is never blocked on writes, usually that involves adjusting following sysctl params on Linux systems:

# percentage of your RAM which can be left unwritten to disk. MUST be much more than
# your write rate, which is usually one FS block size (4KB) per metric.
sysctl -w vm.dirty_ratio = 80

# percentage of yout RAM when background writer have to kick in and
# start writes to disk. Make it way above the value you see in `/proc/meminfo|grep Dirty`
# so that it doesn't interefere with dirty_expire_centisecs explained below
sysctl -w vm.dirty_background_ratio = 50

# allow page to be left dirty no longer than 10 mins
# if unwritten page stays longer than time set here,
# kernel starts writing it out
sysctl -w vm.dirty_expire_centisecs = $(( 10*60*100 ))

Net effect of these 3 params is that with dirty_*_ratio params set high enough multiple updates to a metric don't trigger disk activity. Multiple datapoint writes are coalesced into single disk write which kernel then writes to disk in a background.

With settings above applied, best write-strategy to use is "noop"

Reported stats

metric	description
cache.queueWriteoutTime	Time in seconds to make a full cycle writing all metrics

Changelog

master (unstable, untested)

• Fully refactored and optimizer cache module (core of go-carbon) (thanks Maxim Ivanov)
• Added noop cache.write-strategy (thanks Maxim Ivanov)
• New optional dump/restore functional for minimize data loss on restart
• Refactored internal stat mechanics. common.graph-prefix and common.metric-interval now can be changed without restart (on HUP signal)
• Customizable internal metrics endpoint. common.metric-endpoint param. Valid values: "local" and "" (write directly to whisper), "tcp://host:port", "udp://host:port"

version 0.7.3

• Added cache.write-strategy option (values "max" or "sorted") (thanks Alexander Akulov)
• commitedPoints metric renamed to committedPoints

version 0.7.2

• Added sparse file creation (whisper.sparse-create config option)
• Enable reload in init script (thanks Jose Riguera)
• Clean up schemas parser code (thanks Dieter Plaetinck)
• Better go-whisper error handling (thanks Hiroaki Nakamura)
• Don't try to create whisper file if exists with bad permissions #21

version 0.7.1

• Fixed problem: Points in queue (channel) between cache and persister subsystems was invisible for carbonlink

version 0.7

• Grace stop on USR2 signal: close all socket listeners, flush cache to disk and stop carbon
• Reload persister config (whisper section of main config, storage-schemas.conf and storage-aggregation.conf) on HUP signal
• Fix bug: Cache may start save points only after first checkpoint
• Decimal numbers in log files instead of hexademical #22
• Fix bug: NaN values being saved in Whisper datafiles #17 (thanks Andrew Hayworth)
• Fix bug: may crash on bad pickle message with big message size in header #30. Added option pickle.max-message-size with 64 MB default value
• Improved throttling (max-updates-per-second) performance #32

version 0.6

• metric-interval option

version 0.5.5

• Cache module optimization

version 0.5.4

• Fix RPM init script

version 0.5.3

• Improved validation of bad wsp files
• RPM init script checks config before restart
• Debug logging of bad pickle messages

version 0.5.2

• Fix bug in go-whisper library: UpdateMany saves first point if many points has identical timestamp

version 0.5.1

• Reduced error level of "bad messages" in tcp and pickle receivers. Now info
• Configurable logging level. log-level option
• Fix wrong carbonlink request error in log

version 0.5.0

• -check-config validates schemas and aggregation configs
• Fix broken internal metrics tcp.active and pickle.active
• Optional udp incomplete messages logging: log-incomplete setting
• Fixes for working on x86-32
• logging fsnotify: fix ONCE rotation bug

version 0.4.3

• Optional whisper throttle setting #8: max-updates-per-second

version 0.4.2

• Fix bug in go-whisper: points in long archives missed if metrics retention count >=3

version 0.4.1

• Bug fix schemas parser

version 0.4

• Code refactoring and improved test coverage (thanks Dave Rawks)
• Bug fixes

version 0.3

• Log "create wsp" as debug
• Log UDP checkpoint (calculate stats every minute)
• Rotate logfile by inotify event (without HUP)
• Check logfile opened
• storage-aggregation.conf support
• Create and chown logfile before daemonize and change user
• Debian package (thanks Dave Rawks)

version 0.2

• Git submodule dependencies
• Init script for CentOS 6
• Makefile
• "make rpm" script
• Daemonize and run-as-user support
• -check-config option
• -pidfile option

version 0.1

• First full-functional public version
• Logging with HUP rotation support
• UDP receiver
• Tcp receiver
• Pickle receiver
• TOML-configs
• Carbonlink
• Multi-persister support
• storage-schemas.conf support