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Number of cores as env/context variable ? #25057
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Is there a general way to obtain the number of cores available on the current runner, no matter the OS ? I need to pass this number to some tools I’m using to configure parallelism. |
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Replies: 2 comments 2 replies
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GitHub seems has no predefined environment variables or contexts to get the number of cores. As a workaround, you can run the following commands on each OS to view the number of cores: On Windows: OR On Linux: OR On macOS: Then you can try to get the number from the output of the command, and set an output parameter with using the number as value. In a workflow, The output parameter only can be used between the steps in a same job via the syntax steps.<step_ID>.outputs.<output_name>. If you want to share the output parameter in other jobs, you can try to use artifact to pass the output parameter across jobs. My reply in this ticket shows a simaple demo about how to pass variables/parameters acress jobs. Hope this can help you. |
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On Linux there is the |
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Python is available on all GitHub-hosted runners, so you can use the following on all platforms. steps:
- name: Get the number of CPUs that the current process has access to.
id: cpus
run: |
from os import environ, sched_getaffinity
num_cpus = len(sched_getaffinity(0))
output_file = environ["GITHUB_OUTPUT"]
with open(output_file, "a", encoding="utf-8") as output_stream:
output_stream.write(f"count={num_cpus}\n")
shell: pythonThen you can access the count in subsequent steps via |
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I also think this should be an intrinsic variable provided by GitHub. Here's one workflow that implements the capability using node.js: https://github.com/SimenB/github-actions-cpu-cores |
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GitHub seems has no predefined environment variables or contexts to get the number of cores.
As a workaround, you can run the following commands on each OS to view the number of cores:
On Windows:
OR
On Linux:
OR
On macOS:
Then you can try to get the number from the output of the command, and set an output parameter with using the number as value.
In a workflow, The output parameter only can be used between the steps in a same job via the syntax steps.<step_ID>.outputs.<out…