test.pl: Clarify some comments

Author: khwilliamson

t/test.pl

@@ -1890,8 +1890,7 @@ ($;$)
     # shut up use only once warning
     my $threads_on = $threads::threads && $threads::threads;
 
-    # Don't use a watchdog process if 'threads' is loaded -
-    #   use a watchdog thread instead
+    # Use a watchdog process unless 'threads' is loaded
     if (!$threads_on || $method eq "process") {
 
         # On Windows and VMS, try launching a watchdog process
@@ -1952,8 +1951,8 @@ ($;$)
                 return;
             }
 
-            # Add END block to parent to terminate and
-            #   clean up watchdog process
+            # Add END block to parent to terminate and clean up watchdog
+            # process
             eval("END { local \$! = 0; local \$? = 0;
                         wait() if kill('KILL', $watchdog); };");
             return;
@@ -1964,8 +1963,8 @@ ($;$)
         eval { $watchdog = fork() };
         if (defined($watchdog)) {
             if ($watchdog) {   # Parent process
-                # Add END block to parent to terminate and
-                #   clean up watchdog process
+                # Add END block to parent to terminate and clean up watchdog
+                # process
                 eval "END { local \$! = 0; local \$? = 0;
                             wait() if kill('KILL', $watchdog); };";
                 return;
@@ -2002,8 +2001,8 @@ ($;$)
         # fork() failed - fall through and try using a thread
     }
 
-    # Use a watchdog thread because either 'threads' is loaded,
-    #   or fork() failed
+    # Use a watchdog thread because either 'threads' is loaded, or fork()
+    # failed
     if (eval {require threads; 1}) {
         $watchdog_thread = 'threads'->create(sub {
                 # Load POSIX if available
@@ -2042,7 +2041,8 @@ ($;$)
         return;
     }
 
-    # If everything above fails, then just use an alarm timeout
+    # If everything above fails, then just use an alarm timeout.  There can
+    # only be one in effect at a time.  This cancels any previous one.
 WATCHDOG_VIA_ALARM:
     if (eval { alarm($timeout); 1; }) {
         # Load POSIX if available