meminfo For Node.js

Get memory information on Linux.

Requirements and Installation

Linux, Node.js 24 or later and Rust 1.88 or later are required. Install Rust with rustup and a C compiler for linking.

npm install node-meminfo

Installation compiles the native module from source using the included Cargo.lock. There are no prebuilt platform packages. Package managers that block dependency build scripts must allow the node-meminfo install script; for pnpm, approve node-meminfo with pnpm approve-builds and rebuild it with pnpm rebuild node-meminfo. If npm requires script approval, use npm install-scripts approve node-meminfo followed by npm rebuild node-meminfo.

Usage

meminfo

The meminfo function gets all fields and values from /proc/meminfo. The values are in bytes, except the HugePages_* fields, which are page counts.

import { meminfo } from "node-meminfo";

console.log(meminfo());
/*
{
    MemTotal: 66645020672,
    MemFree: 914055168,
    MemAvailable: 45735542784,
    Buffers: 2629632,
    Cached: 42922389504,
    SwapCached: 8396800,
    Active: 11555053568,
    Inactive: 46985338880,
    'Active(anon)': 8459821056,
    'Inactive(anon)': 8526344192,
    'Active(file)': 3095232512,
    'Inactive(file)': 38458994688,
    Unevictable: 93741056,
    Mlocked: 114688,
    SwapTotal: 8192520192,
    SwapFree: 6442967040,
    Zswap: 0,
    Zswapped: 0,
    Dirty: 1622016,
    Writeback: 0,
    AnonPages: 15701975040,
    Mapped: 2233372672,
    Shmem: 1370796032,
    KReclaimable: 4012236800,
    Slab: 5578682368,
    SReclaimable: 4012236800,
    SUnreclaim: 1566445568,
    KernelStack: 59473920,
    PageTables: 204087296,
    SecPageTables: 8339456,
    NFS_Unstable: 0,
    Bounce: 0,
    WritebackTmp: 0,
    CommitLimit: 41515028480,
    Committed_AS: 89246199808,
    VmallocTotal: 35184372087808,
    VmallocUsed: 193331200,
    VmallocChunk: 0,
    Percpu: 26640384,
    HardwareCorrupted: 0,
    AnonHugePages: 79691776,
    ShmemHugePages: 25165824,
    ShmemPmdMapped: 0,
    FileHugePages: 0,
    FilePmdMapped: 0,
    CmaTotal: 0,
    CmaFree: 0,
    Unaccepted: 0,
    Balloon: 0,
    HugePages_Total: 0,
    HugePages_Free: 0,
    HugePages_Rsvd: 0,
    HugePages_Surp: 0,
    Hugepagesize: 2097152,
    Hugetlb: 0,
    DirectMap4k: 12566372352,
    DirectMap2M: 54299459584,
    DirectMap1G: 3221225472
}
*/

free

If you like to use the free command on Linux, you probably prefer to use the free function. It returns the same values as free -b -w of procps-ng 4.

import { free } from "node-meminfo";

console.log(free());
/*
{
    mem: {
        total: 66645020672,
        used: 20909477888,
        free: 914055168,
        shared: 1370796032,
        buffers: 2629632,
        cache: 46934626304,
        available: 45735542784
    },
    swap: {
        total: 8192520192,
        used: 1749553152,
        free: 6442967040,
        cache: 8396800
    }
}
*/

All values are in bytes and are calculated from the fields of /proc/meminfo as follows.

Field	Calculation
mem.total	MemTotal
mem.used	MemTotal - MemAvailable
mem.free	MemFree
mem.shared	Shmem
mem.buffers	Buffers
mem.cache	Cached + SReclaimable
mem.available	MemAvailable
swap.total	SwapTotal
swap.used	SwapTotal - SwapFree
swap.free	SwapFree
swap.cache	SwapCached

Like procps-ng, MemFree is used as MemAvailable if MemAvailable is missing or larger than MemTotal (for example, in some LXC containers).

License

MIT