Lib.rs

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The current version of num_cpus is 1.16.0.

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safe-to-deploy (implies safe-to-run)

This crate will not introduce a serious security vulnerability to production software exposed to untrusted input. More…

safe-to-run

This crate can be compiled, run, and tested on a local workstation or in controlled automation without surprising consequences. More…

does-not-implement-crypto (implies crypto-safe)

Inspection reveals that the crate in question does not attempt to implement any cryptographic algorithms on its own.

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crypto-safe
Implied by other criteria

All crypto algorithms in this crate have been reviewed by a relevant expert.

Note: If a crate does not implement crypto, use does-not-implement-crypto, which implies crypto-safe, but does not require expert review in order to audit for.

unknown

May have been packaged automatically without a review

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The current version of num_cpus is 1.16.0.

1.13.0 (older version) Rating: Positive Thoroughness: Low Understanding: Low

by MaulingMonkey on 2020-09-07

Queries the OS for the number of CPU cores you have.

Pros:

  • You didn't have to write it.
  • Handles all that hideously platform specific nonsense for you.

Cons:

  • Lots of (necessary) unsafe
  • Linux cgroups support seems wildly overcomplicated.
  • Lies and lies and lies and lies. Not exactly this crate's fault - the system APIs are brittle and full of edge cases. Multi-processor architectures are full of edge cases.

Alternatives:

  • Just hardcode a reasonable number of threads for your workload! Spinning up threads for 64 CPU cores to all false-share a single cacheline because that's how many logical cores were detected isn't the right choice! And all your threads are probably blocked on I/O anyways!

Full Audit

1.12.0 (older version) Rating: Positive Thoroughness: Medium Understanding: Medium

by MaulingMonkey on 2020-09-07

Show review…

Queries the OS for the number of CPU cores you have.

Pros:

  • You didn't have to write it.
  • Handles all that hideously platform specific nonsense for you.

Cons:

  • Lots of (necessary) unsafe
  • Linux cgroups support seems wildly overcomplicated.
  • Lies and lies and lies and lies. Not exactly this crate's fault - the system APIs are brittle and full of edge cases. Multi-processor architectures are full of edge cases.

Alternatives:

  • Just hardcode a reasonable number of threads for your workload! Spinning up threads for 64 CPU cores to all false-share a single cacheline because that's how many logical cores were detected isn't the right choice! And all your threads are probably blocked on I/O anyways!

Full Audit

1.10.1 (older version) Rating: Positive Thoroughness: Medium Understanding: Medium

Approved without comment by dpc on 2019-07-03

Lib.rs has been able to verify that all files in the crate's tarball, except Cargo.lock, are in the crate's repository with a git tag matching the version. Please note that this check is still in beta, and absence of this confirmation does not mean that the files don't match.

Crates in the crates.io registry are tarball snapshots uploaded by crates' publishers. The registry is not using crates' git repositories, so there is a possibility that published crates have a misleading repository URL, or contain different code from the code in the repository.

To review the actual code of the crate, it's best to use cargo crev open num_cpus. Alternatively, you can download the tarball of num_cpus v1.16.0 or view the source online.