53 lines
1.6 KiB
Markdown
53 lines
1.6 KiB
Markdown
# numcpus
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[](https://pkg.go.dev/github.com/tklauser/numcpus)
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[](https://github.com/tklauser/numcpus/actions?query=workflow%3ATests)
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Package numcpus provides information about the number of CPUs in the system.
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It gets the number of CPUs (online, offline, present, possible, configured or
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kernel maximum) on Linux, Darwin, FreeBSD, NetBSD, OpenBSD, DragonflyBSD or
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Solaris/Illumos systems.
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On Linux, the information is retrieved by reading the corresponding CPU
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topology files in `/sys/devices/system/cpu`.
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On BSD systems, the information is retrieved using the `hw.ncpu` and
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`hw.ncpuonline` sysctls, if supported.
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Not all functions are supported on Darwin, FreeBSD, NetBSD, OpenBSD,
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DragonflyBSD and Solaris/Illumos. ErrNotSupported is returned in case a
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function is not supported on a particular platform.
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## Usage
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```Go
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package main
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import (
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"fmt"
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"os"
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"github.com/tklauser/numcpus"
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)
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func main() {
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online, err := numcpus.GetOnline()
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if err != nil {
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fmt.Fprintf(os.Stderr, "GetOnline: %v\n", err)
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}
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fmt.Printf("online CPUs: %v\n", online)
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possible, err := numcpus.GetPossible()
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if err != nil {
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fmt.Fprintf(os.Stderr, "GetPossible: %v\n", err)
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}
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fmt.Printf("possible CPUs: %v\n", possible)
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}
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```
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## References
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* [Linux kernel sysfs documentation for CPU attributes](https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-devices-system-cpu)
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* [Linux kernel CPU topology documentation](https://www.kernel.org/doc/Documentation/cputopology.txt)
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