Zoltan Kochan
aaaca889de
APFS serializes metadata-write syscalls volume-wide: measured against a warm store, clonefile(2) throughput never exceeds its single-thread rate no matter how many threads issue it, and link(2) scales negatively. Importing packages one CAS file at a time from a rayon-wide fan-out therefore sits at a per-volume ceiling, and the kernel lock convoy behind that ceiling deepens with core count — which is how a warm-store install that rebuilds node_modules got several times slower than pnpm 11's libuv-4-thread importer on many-core Macs. Instead of tuning thread counts against a machine-dependent contention curve, cut the syscall count: materialize each package once into the canonical global-virtual-store slot under <store>/v11/links (the same layout, completion-marker protocol, and concurrent-writer healing that enableGlobalVirtualStore installs already use), then project it into the project-local virtual store with one directory clonefile(2) per package. A hot install whose canonical slots already exist pays one stat and one clonefile per package instead of one syscall per file: on a 60-project / 1354-package / 44k-file workspace fixture, rebuilding node_modules from a warm store drops from 10-14s to ~4.4s (pnpm 11: ~14.7s), while the canonical-populating first install stays at the old per-file cost. The resulting node_modules is byte-identical to the per-file path's. The cache engages only on macOS, under the isolated linker, with the local virtual store, when the import method may clone (auto, clone, clone-or-copy). Slots that need a build or patch marker, come from mutable local sources, are force-re-imported, or resolve without a checkable integrity (git dependencies, whose slot hash cannot see whether their fetch-time prepare ran) keep the per-file path, so canonical slots always hold plain pre-build CAS content and stay interchangeable with what a GVS-enabled install materializes before its build phase. Slots are addressed only through the content-addressed graph-hash suffix, and the engine name is resolved synchronously for eligible installs so those hashes agree with GVS installs sharing the store. Every cache failure falls back to the per-file import; failures that condemn the volume (EXDEV, ENOTSUP) disable the cache for the rest of the process. The pnpm 11 TypeScript CLI keeps its per-file importer: it cannot issue a directory clonefile through libuv, its 4-thread pool sits near the APFS ceiling already, and materialization strategy is not part of the cross-stack contract. Like the Linux hardlink-first Auto ladder, this is a v12-only materialization difference shipped behind the major. Closes pnpm/pnpm#14231.
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Fast, disk space efficient package manager:
- Fast. Up to 2x faster than the alternatives (see benchmark).
- Efficient. Files inside
node_modulesare linked from a single content-addressable storage. - Great for monorepos.
- Strict. A package can access only dependencies that are specified in its
package.json. - Deterministic. Has a lockfile called
pnpm-lock.yaml. - Works as a Node.js version manager. See pnpm runtime.
- Works everywhere. Supports Windows, Linux, and macOS.
- Battle-tested. Used in production by teams of all sizes since 2016.
- Experimental Rust port. Includes pacquet, an experimental port of the CLI written in Rust.
- See the full feature comparison with npm and Yarn.
To quote the Rush team:
Microsoft uses pnpm in Rush repos with hundreds of projects and hundreds of PRs per day, and we’ve found it to be very fast and reliable.
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Background
pnpm uses a content-addressable filesystem to store all files from all module directories on a disk. When using npm, if you have 100 projects using lodash, you will have 100 copies of lodash on disk. With pnpm, lodash will be stored in a content-addressable storage, so:
- If you depend on different versions of lodash, only the files that differ are added to the store.
If lodash has 100 files, and a new version has a change only in one of those files,
pnpm updatewill only add 1 new file to the storage. - All the files are saved in a single place on the disk. When packages are installed, their files are linked from that single place consuming no additional disk space. Linking is performed using either hard-links or reflinks (copy-on-write).
As a result, you save gigabytes of space on your disk and you have a lot faster installations!
If you'd like more details about the unique node_modules structure that pnpm creates and
why it works fine with the Node.js ecosystem, read this small article: Flat node_modules is not the only way.
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Getting Started
Benchmark
pnpm is up to 2x faster than npm and Yarn classic. See all benchmarks here.
Benchmarks on an app with lots of dependencies:
License
MIT, except the pnpr/ directory, which is source-available under the PolyForm Shield License 1.0.0.