Memcached

Plugin: python.d.plugin Module: memcached

Overview

Monitor Memcached metrics for proficient in-memory key-value store operations. Track cache hits, misses, and memory usage for efficient data caching.

It reads server response to stats command (stats interface).

This collector is supported on all platforms.

This collector supports collecting metrics from multiple instances of this integration, including remote instances.

Default Behavior

Auto-Detection

If no configuration is given, collector will attempt to connect to memcached instance on 127.0.0.1:11211 address.

Limits

The default configuration for this integration does not impose any limits on data collection.

Performance Impact

The default configuration for this integration is not expected to impose a significant performance impact on the system.

Metrics

Metrics grouped by scope.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.

Per Memcached instance

These metrics refer to the entire monitored application.

This scope has no labels.

Metrics:

Metric	Dimensions	Unit
memcached.cache	available, used	MiB
memcached.net	in, out	kilobits/s
memcached.connections	current, rejected, total	connections/s
memcached.items	current, total	items
memcached.evicted_reclaimed	reclaimed, evicted	items
memcached.get	hints, misses	requests
memcached.get_rate	rate	requests/s
memcached.set_rate	rate	requests/s
memcached.delete	hits, misses	requests
memcached.cas	hits, misses, bad value	requests
memcached.increment	hits, misses	requests
memcached.decrement	hits, misses	requests
memcached.touch	hits, misses	requests
memcached.touch_rate	rate	requests/s

Alerts

The following alerts are available:

Alert name	On metric	Description
memcached_cache_memory_usage	memcached.cache	cache memory utilization
memcached_cache_fill_rate	memcached.cache	average rate the cache fills up (positive), or frees up (negative) space over the last hour
memcached_out_of_cache_space_time	memcached.cache	estimated time the cache will run out of space if the system continues to add data at the same rate as the past hour

Setup

Prerequisites

No action required.

Configuration

File

The configuration file name for this integration is python.d/memcached.conf.

You can edit the configuration file using the edit-config script from the Netdata config directory.

cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config python.d/memcached.conf

Options

There are 2 sections:

• Global variables
• One or more JOBS that can define multiple different instances to monitor.

The following options can be defined globally: priority, penalty, autodetection_retry, update_every, but can also be defined per JOB to override the global values.

Additionally, the following collapsed table contains all the options that can be configured inside a JOB definition.

Every configuration JOB starts with a job_name value which will appear in the dashboard, unless a name parameter is specified.

Config options

Name	Description	Default	Required
host	the host to connect to.	127.0.0.1	no
port	the port to connect to.	11211	no
update_every	Sets the default data collection frequency.	10	no
priority	Controls the order of charts at the netdata dashboard.	60000	no
autodetection_retry	Sets the job re-check interval in seconds.	0	no
penalty	Indicates whether to apply penalty to update_every in case of failures.	yes	no
name	Job name. This value will overwrite the job_name value. JOBS with the same name are mutually exclusive. Only one of them will be allowed running at any time. This allows autodetection to try several alternatives and pick the one that works.		no

Examples

localhost

An example configuration for localhost.

localhost:
  name: 'local'
  host: 'localhost'
  port: 11211

localipv4

An example configuration for localipv4.

Config

localhost:
  name: 'local'
  host: '127.0.0.1'
  port: 11211

localipv6

An example configuration for localipv6.

Config

localhost:
  name: 'local'
  host: '::1'
  port: 11211

Troubleshooting

Debug Mode

To troubleshoot issues with the memcached collector, run the python.d.plugin with the debug option enabled. The output should give you clues as to why the collector isn't working.

• Navigate to the plugins.d directory, usually at /usr/libexec/netdata/plugins.d/. If that's not the case on your system, open netdata.conf and look for the plugins setting under [directories].

  cd /usr/libexec/netdata/plugins.d/

• Switch to the netdata user.

  sudo -u netdata -s

• Run the python.d.plugin to debug the collector:

  ./python.d.plugin memcached debug trace