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Memcached

Plugin: go.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 the server's response to the stats command.

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:

MetricDimensionsUnit
memcached.cacheavailable, usedMiB
memcached.netin, outkilobits/s
memcached.connectionscurrent, rejected, totalconnections/s
memcached.itemscurrent, totalitems
memcached.evicted_reclaimedreclaimed, evicteditems
memcached.gethints, missesrequests
memcached.get_rateraterequests/s
memcached.set_rateraterequests/s
memcached.deletehits, missesrequests
memcached.cashits, misses, bad valuerequests
memcached.incrementhits, missesrequests
memcached.decrementhits, missesrequests
memcached.touchhits, missesrequests
memcached.touch_rateraterequests/s

Alerts

The following alerts are available:

Alert nameOn metricDescription
memcached_cache_memory_usage memcached.cachecache memory utilization
memcached_cache_fill_rate memcached.cacheaverage rate the cache fills up (positive), or frees up (negative) space over the last hour
memcached_out_of_cache_space_time memcached.cacheestimated 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 go.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 go.d/memcached.conf

Options

The following options can be defined globally: update_every, autodetection_retry.

Config options
NameDescriptionDefaultRequired
update_everyData collection frequency.1no
autodetection_retryRecheck interval in seconds. Zero means no recheck will be scheduled.0no
addressThe IP address and port where the memcached service listens for connections.127.0.0.1:11211yes
timeoutConnection, read, and write timeout duration in seconds. The timeout includes name resolution.1no

Examples

Basic

A basic example configuration.

Config
jobs:
- name: local
address: 127.0.0.1:11211

Multi-instance

Note: When you define multiple jobs, their names must be unique.

Collecting metrics from local and remote instances.

Config
jobs:
- name: local
address: 127.0.0.1:11211

- name: remote
address: 203.0.113.0:11211

Troubleshooting

Debug Mode

Important: Debug mode is not supported for data collection jobs created via the UI using the Dyncfg feature.

To troubleshoot issues with the memcached collector, run the go.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 go.d.plugin to debug the collector:

    ./go.d.plugin -d -m memcached

Getting Logs

If you're encountering problems with the memcached collector, follow these steps to retrieve logs and identify potential issues:

  • Run the command specific to your system (systemd, non-systemd, or Docker container).
  • Examine the output for any warnings or error messages that might indicate issues. These messages should provide clues about the root cause of the problem.

System with systemd

Use the following command to view logs generated since the last Netdata service restart:

journalctl _SYSTEMD_INVOCATION_ID="$(systemctl show --value --property=InvocationID netdata)" --namespace=netdata --grep memcached

System without systemd

Locate the collector log file, typically at /var/log/netdata/collector.log, and use grep to filter for collector's name:

grep memcached /var/log/netdata/collector.log

Note: This method shows logs from all restarts. Focus on the latest entries for troubleshooting current issues.

Docker Container

If your Netdata runs in a Docker container named "netdata" (replace if different), use this command:

docker logs netdata 2>&1 | grep memcached

Do you have any feedback for this page? If so, you can open a new issue on our netdata/learn repository.