A 40ms Go garbage collector pause caused by swap
A software engineer discovered that running a Go application with swap memory enabled can lead to significant performance degradation. The garbage collector's stop-the-world pauses were extended to 40ms due to page faults occurring when the system accessed swapped-out metadata.
Why it matters
This highlights a critical performance pitfall for developers managing memory-intensive Go applications in production environments where swap is enabled.
I'm writing this so you don't slap your forehead like I almost did when I decided to run swap in production to absorb memory spikes.
I had a cgroup with two processes: one is a Go process that calls io.ReadAll and then proto.Unmarshal , creating a blob and then a graph struct (which is marked as scan by Go's allocator). The other process is an HTTP server that mostly stays quiet.
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