X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/fe33cfe407912df46ae34b5419ebdc84650829f6..d3cef2f89fbcbf9bac380a7c834f13117d187058:/services/crunch-run/background.go

diff --git a/services/crunch-run/background.go b/services/crunch-run/background.go
index a508538370..334b3ab674 100644
--- a/services/crunch-run/background.go
+++ b/services/crunch-run/background.go
@@ -49,14 +49,15 @@ func detach(uuid string, args []string, stdout, stderr io.Writer) error {
 			return nil, err
 		}
 		defer dirlock.Close()
-		lockfile, err := os.OpenFile(filepath.Join(lockdir, lockprefix+uuid+locksuffix), os.O_CREATE|os.O_RDWR, 0700)
+		lockfilename := filepath.Join(lockdir, lockprefix+uuid+locksuffix)
+		lockfile, err := os.OpenFile(lockfilename, os.O_CREATE|os.O_RDWR, 0700)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("open %s: %s", lockfilename, err)
 		}
 		err = syscall.Flock(int(lockfile.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
 		if err != nil {
 			lockfile.Close()
-			return nil, err
+			return nil, fmt.Errorf("lock %s: %s", lockfilename, err)
 		}
 		return lockfile, nil
 	}()
@@ -91,7 +92,7 @@ func detach(uuid string, args []string, stdout, stderr io.Writer) error {
 	if err != nil {
 		os.Remove(outfile.Name())
 		os.Remove(errfile.Name())
-		return err
+		return fmt.Errorf("exec %s: %s", cmd.Path, err)
 	}
 
 	w := io.MultiWriter(stdout, lockfile)
@@ -123,14 +124,14 @@ func kill(uuid string, signal syscall.Signal, stdout, stderr io.Writer) error {
 	if os.IsNotExist(err) {
 		return nil
 	} else if err != nil {
-		return err
+		return fmt.Errorf("open %s: %s", path, err)
 	}
 	defer f.Close()
 
 	var pi procinfo
 	err = json.NewDecoder(f).Decode(&pi)
 	if err != nil {
-		return fmt.Errorf("%s: %s\n", path, err)
+		return fmt.Errorf("decode %s: %s\n", path, err)
 	}
 
 	if pi.UUID != uuid || pi.PID == 0 {
@@ -139,7 +140,7 @@ func kill(uuid string, signal syscall.Signal, stdout, stderr io.Writer) error {
 
 	proc, err := os.FindProcess(pi.PID)
 	if err != nil {
-		return err
+		return fmt.Errorf("%s: find process %d: %s", uuid, pi.PID, err)
 	}
 
 	err = proc.Signal(signal)
@@ -147,16 +148,19 @@ func kill(uuid string, signal syscall.Signal, stdout, stderr io.Writer) error {
 		err = proc.Signal(syscall.Signal(0))
 	}
 	if err == nil {
-		return fmt.Errorf("pid %d: sent signal %d (%s) but process is still alive", pi.PID, signal, signal)
+		return fmt.Errorf("%s: pid %d: sent signal %d (%s) but process is still alive", uuid, pi.PID, signal, signal)
 	}
-	fmt.Fprintf(stderr, "pid %d: %s\n", pi.PID, err)
+	fmt.Fprintf(stderr, "%s: pid %d: %s\n", uuid, pi.PID, err)
 	return nil
 }
 
 // List UUIDs of active crunch-run processes.
 func ListProcesses(stdout, stderr io.Writer) int {
-	return exitcode(stderr, filepath.Walk(lockdir, func(path string, info os.FileInfo, err error) error {
-		if info.IsDir() {
+	// filepath.Walk does not follow symlinks, so we must walk
+	// lockdir+"/." in case lockdir itself is a symlink.
+	walkdir := lockdir + "/."
+	return exitcode(stderr, filepath.Walk(walkdir, func(path string, info os.FileInfo, err error) error {
+		if info.IsDir() && path != walkdir {
 			return filepath.SkipDir
 		}
 		if name := info.Name(); !strings.HasPrefix(name, lockprefix) || !strings.HasSuffix(name, locksuffix) {
@@ -186,7 +190,7 @@ func ListProcesses(stdout, stderr io.Writer) int {
 			err := os.Remove(path)
 			dirlock.Close()
 			if err != nil {
-				fmt.Fprintln(stderr, err)
+				fmt.Fprintf(stderr, "unlink %s: %s\n", f.Name(), err)
 			}
 			return nil
 		}
@@ -224,14 +228,15 @@ func exitcode(stderr io.Writer, err error) int {
 //
 // Caller releases the lock by closing the returned file.
 func lockall() (*os.File, error) {
-	f, err := os.OpenFile(filepath.Join(lockdir, lockprefix+"all"+locksuffix), os.O_CREATE|os.O_RDWR, 0700)
+	lockfile := filepath.Join(lockdir, lockprefix+"all"+locksuffix)
+	f, err := os.OpenFile(lockfile, os.O_CREATE|os.O_RDWR, 0700)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("open %s: %s", lockfile, err)
 	}
 	err = syscall.Flock(int(f.Fd()), syscall.LOCK_EX)
 	if err != nil {
 		f.Close()
-		return nil, err
+		return nil, fmt.Errorf("lock %s: %s", lockfile, err)
 	}
 	return f, nil
 }