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Monitoring Node.js


A light-weight, open-source Node.js monitoring agent collects Node.js processes' metrics and sends them to Sematext. It is available as npm package that can be added to the JavaScript source code like any other Node.js module.

The following metrics are collected:

  • Operating System

    • CPU usage
    • Memory usage
  • Process Memory Usage

  • Number of Worker processes (when using "cluster" package for master/worker processes)

  • Event Loop

    • Latencies (fastest, slowest, average)
  • Garbage Collection (GC)

    • Counters for full GC
    • Counters for incremental GC
    • Time spend for GC
    • Difference in heap used after each GC cycle
  • HTTP Server stats

    • Request count
    • Request rate
    • Content-Length
    • Error rates (total, 3xx, 4xx, 5xx)


Generate diagnostics file for Sematext Support

If you are not seeing some or any Node.js metrics, you can create a "diagnostics dump" and contact us via chat or email. To create the diagnostics dump just run the following in your application directory:

node ./node_modules/spm-agent-nodejs/bin/spm-client-diagnostics.js

This will create a ZIP file and show the Sematext Support email address to which the ZIP file should be sent.



Metric Name Key Agg Type Description
heap total nodejs.heap.size Avg Long
heap used nodejs.heap.used Avg Long
total released nodejs.gc.heap.diff Sum Double
total duration nodejs.gc.time Sum Double
full gc nodejs.gc.full Sum Long
inc gc Sum Long
memory rss nodejs.memory.rss Avg Long
workers count nodejs.workers Avg Long
request count nodejs.requests Sum Long
error count nodejs.errors Sum Long
5xx count nodejs.errors.5xx Sum Long
4xx count nodejs.errors.4xx Sum Long
3xx count nodejs.errors.3xx Sum Long
total req. size Sum Long
total res. size Sum Long
min response latency nodejs.responses.latency.min Min Long
max response latency nodejs.responses.latency.max Max Long
min latency nodejs.eventloop.latency.min Min Long
max latency nodejs.eventloop.latency.max Max Long

Custom Metrics

To track custom metrics likethe number of concurrent users, the number of items placed in a shopping cart, or any other kind of business transaction or KPI we provide a Custom Metrics API and a Node.js client for it: spm-metrics-js


Can I install spm-agent-nodejs on Windows?

Yes. The native modules are automatically compiled during "npm install" (using node-gyp). On Windows the required build tools like python or C++ compilers are typically not installed by default. See for details about the required compiler and build tools.

How can I configure spm-agent-nodejs for my app using PM2 process manager?

Install spm-agent-nodejs as global module:

sudo npm i -g spm-agent-nodejs

Check the location (full path) for spm-agent-nodejs using:

sudo npm root -g

The result is typically /usr/local/lib/node_modules or /usr/lib/node_modules. Remember the path to use it in the "interpreter_args" step below in the PM2 configuration file.

If you use PM2 to start your Node.js process, then use the following environment section in your PM2 application config file:

   "interpreter_args": "-r /usr/local/lib/node_modules/spm-agent-nodejs"
   "env": { 
      "spmagent_dbDir": "./spmdb",
      "spmagent_logger__dir": "./spmlogs",
      "spmagent_logger__silent" = false,
      "spmagent_logger__level": "error"

How can I use spm-agent-nodejs behind Firewalls / Proxy servers?

By default data is transmitted via HTTPS. If no direct connection is possible, a proxy server can be used by setting the environment variable HTTPS_PROXY=https://your-proxy.

What should I do after upgrading to a new Node.js version?

If you switch the Node.jsversion the spm-agent-nodejs package will need to be installed again (due to the fact that included native modules may change from version to version). After the version change please run a fresh "npm install" if you added spm-agent-nodejs to the dependencies in your package.json or at the very least run "npm install spm-agent-nodejs".

How do I upgrade to the latest version of spm-agent-nodejs?

To use the latest version of spm-agent-nodejs we recommend you install/upgrade using:

npm install spm-agent-nodejs@latest

To add the dependency to your package.json simply use:

npm install spm-agent-nodejs@latest--save