golabels: ignore attach when Go plugins are loaded#1314
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christos68k merged 3 commits intoApr 3, 2026
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When a Go process loads shared libraries via plugin.Open(), the profiler creates separate golabels interpreter instances for each Go ELF file in the process. Since they all share the same PID-keyed eBPF map entry, the second Detach fails with "key does not exist". Fix by wrapping the error in DeleteProcData with %w so callers can inspect it, and ignoring ErrKeyNotExist in golabels Detach. Fixes open-telemetry#1301
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Thanks! Maybe add a debug log line if something actually goes wrong with golabels in a multi-plugin process?
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| if err := ebpf.DeleteProcData(libpf.GoLabels, pid); err != nil && !errors.Is(err, cebpf.ErrKeyNotExist) { | ||
| return err | ||
| } | ||
| return nil |
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This would also incorporate #1314 (comment):
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| if err := ebpf.DeleteProcData(libpf.GoLabels, pid); err != nil && !errors.Is(err, cebpf.ErrKeyNotExist) { | |
| return err | |
| } | |
| return nil | |
| err := ebpf.DeleteProcData(libpf.GoLabels, pid) | |
| switch { | |
| case err == nil: return | |
| case errors.Is(err, cebpf.ErrKeyNotExist): | |
| log.Debugf("Entry for PID %d already removed", pid) | |
| return nil | |
| default: | |
| return err | |
| } |
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Don't need the err == nil case I think, I pushed a commit to add logging.
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| func (d *data) Detach(ebpf interpreter.EbpfHandler, pid libpf.PID) error { | ||
| return ebpf.DeleteProcData(libpf.GoLabels, pid) | ||
| // Go plugins share the runtime with the main binary, so multiple Go ELF |
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It it worth further clarifying that Go does not support unloading plugins here? If one doesn't know that then one could think that we still have an issue.
Go plugins can't change go labels version/offset information nor the TLS information so ignore them by detecting when a go exe is a shared object.
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I completely flipped this on its head and think its better to just ignore Go plugins, please take another look, thanks! |
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When a Go process loads shared libraries via
plugin.Open(), the profiler creates separategolabelsinterpreter instances for each Go ELF file in the process. Since Go plugins must be built with the same Go version as the host binary and share the runtime, they produce identicalGoLabelsOffsets— but both instances write and delete the same PID-keyed eBPF map entry.The second
Detachcall fails with "key does not exist" because the first instance already removed it.This fixes the issue by ignoring the attach of Go plugins, since the proc data would be the same there's no point in maintaining a golabels instance for it.
Fixes #1301