Fix SIGBUS race in CPUInstall by extracting to temp dir first#17
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CPUInstall previously extracted the PJRT plugin .so directly to its final install path via Untar. When go test runs multiple packages in parallel, concurrent CPUAutoInstall calls could race: one goroutine writes the .so via Untar while another sees the partially-written file via os.Stat, skips installation, and dlopen-s it — causing SIGBUS. Fix: extract to a temporary directory (.extracting-*) inside the install path, then os.Rename each file to its final location. Since the temp dir is on the same filesystem, os.Rename is atomic — the .so transitions from nonexistent to complete in a single syscall. This matches the pattern already used by DownloadURLToTemp for downloads (.tmp + rename), now applied to the extraction step.
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CPUInstall previously extracted the PJRT plugin .so directly to its final install path via Untar. When go test runs multiple packages in parallel, concurrent CPUAutoInstall calls could race: one goroutine writes the .so via Untar while another sees the partially-written file via os.Stat, skips installation, and dlopen-s it, causing SIGBUS.
Fix: extract to a temporary directory (.extracting-*) inside the install path, then os.Rename each file to its final location. Since the temp dir is on the same filesystem, os.Rename is atomic, the .so transitions from nonexistent to complete in a single syscall.
This matches the pattern already used by DownloadURLToTemp for downloads (.tmp + rename), now applied to the extraction step.