Memcached icon

Memcached

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.

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.

Name Description Default Required
update_every Data collection frequency. 1 no
autodetection_retry Recheck interval in seconds. Zero means no recheck will be scheduled. 0 no
address The IP address and port where the memcached service listens for connections. 127.0.0.1:11211 yes
timeout Connection, read, and write timeout duration in seconds. The timeout includes name resolution. 1 no

Examples

Basic

A basic example configuration.

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.

jobs:
  - name: local
    address: 127.0.0.1:11211

  - name: remote
    address: 203.0.113.0:11211

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

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

The observability platform companies need to succeed

Sign up for free

Want a personalised demo of Netdata for your use case?

Book a Demo