A readable stream that samples and emits memory usage over time
npm install memory-usageA readable stream that samples and emits memory usage over time.
You can for instance use the output to graph your memory usage.
Can also be used from the command line to chart the memory usage of a
Node.js app directly in a web browser.
For CLI usage:
``
npm install memory-usage -g
For programmatic usage:
`
npm install memory-usage --save
Use the memory-usage command instead of the node command:
`
memory-usage server.js
The memory usage of server.js will now be displayed live in your default web browser:
Sample memory usage every 2 seconds and write it to a CSV file:
`js
var fs = require('fs')
var csvWriter = require('csv-write-stream')
var memoryUsage = require('memory-usage')
memoryUsage(2000)
.pipe(csvWriter())
.pipe(fs.createWriteStream('memory.csv'))
`
Note that you application of course have to do some actual work. If you
just run the example above as is, the node process will simply exit
after creating an empty file.
If you want to chart the memory usage, I recommend combining this module
with chart-csv.
Will start sampling memory usage every freq milliseconds (defaults to5000) as soon as the stream is flowing.
The optional options object expects the following properties:
- freq - The sampling frequency in milliseconds (defaults to 5000)ts
- - A boolean specifying if a timestamp should be outputtet alongfalse
with the memory samples (defaults to )gc
- - A boolean specifying if garbage collection should be profiledfalse
and logged along with the memory samples (defaults to )
The stream emits samples in the form of JavaScript objects:
`jsoptsions.ts
{
rss: 4935680, // Resident set size: Memory assigned to the process in bytes
heapTotal: 1826816, // V8 heap memory allocated in bytes
heapUsed: 650472, // V8 heap memory used in bytes
ts: 1479179912921, // UNIX epoch timestamp for sample in milliseconds (only present if is true)options.gc
gc: null // Indicates if sample was taken after a garbage collection run (only present if is true)`
}
If the gc property is null, it means that the sample wasn't takenScavenge
after a garbage collection run. If the value is a string, it will
indicate the type of garbage collection run. Currently, the values can
be either or MarkSweepCompact`.
Note that samples indicating a garbage collection run might be a few
hundred milliseconds delayed. This means that you might see a regular
timed sample appear prior in the stream with reduced memory usage, even
though there's no official indication of a garbage collection run yet.
MIT