Uros investigated a libgo testsuite failure on Alpha GNU/Linux that looked like a GC bug but turned out to simply be a testsuite bug. In Go when the garbage collector collects an os.File it closes the file descriptor. The syscall/creds_test test would call socketpair(), and defer closing both descriptors. Then it would turn the file descriptors into os.File pointers using os.NewFile, but it would not close those os.File pointers. So when the test returned, the file descriptors would be closed, but the os.File pointers would remain in the heap, inaccessible. When the garbage collector noticed that, it would run the finalizers, and close the descriptors again. That is normally harmless, as the finalizer ignored the errors. However, in this case a later test would call socketpair again and happened to get the same file descriptor numbers back. Then the garbage collector ran, and closed them before the test was complete. So the test failed.
This patch fixes the problem. Test ran on x86_64-unknown-linux-gnu. Committed to mainline. Ian
diff -r 158890b70d33 libgo/go/syscall/creds_test.go --- a/libgo/go/syscall/creds_test.go Thu Oct 25 11:25:35 2012 -0700 +++ b/libgo/go/syscall/creds_test.go Fri Oct 26 10:38:15 2012 -0700 @@ -31,14 +31,18 @@ t.Fatalf("SetsockoptInt: %v", err) } - srv, err := net.FileConn(os.NewFile(uintptr(fds[0]), "")) + srvFile := os.NewFile(uintptr(fds[0]), "server") + defer srvFile.Close() + srv, err := net.FileConn(srvFile) if err != nil { t.Errorf("FileConn: %v", err) return } defer srv.Close() - cli, err := net.FileConn(os.NewFile(uintptr(fds[1]), "")) + cliFile := os.NewFile(uintptr(fds[1]), "client") + defer cliFile.Close() + cli, err := net.FileConn(cliFile) if err != nil { t.Errorf("FileConn: %v", err) return