autotest: fixed killing of Xvfb

this should make fly.ArduPlane more reliable

Tools/autotest/arduplane.py

@@ -217,9 +217,12 @@ def fly_ArduPlane(viewerip=None):
     # start fgear
     if os.getenv('DISPLAY'):
         cmd = 'fgfs %s' % fgear_options
+        fgear = pexpect.spawn(cmd, logfile=sys.stdout, timeout=10)
     else:
-        cmd = "xvfb-run -s '-screen 0 800x600x24' fgfs --enable-wireframe %s" % fgear_options
-    fgear = pexpect.spawn(cmd, logfile=sys.stdout, timeout=10)
+        cmd = "xvfb-run --server-num=42 -s '-screen 0 800x600x24' fgfs --enable-wireframe %s" % fgear_options
+        util.kill_xvfb(42)
+        fgear = pexpect.spawn(cmd, logfile=sys.stdout, timeout=10)
+        fgear.xvfb_server_num = 42
     util.pexpect_autoclose(fgear)
 
     expect_list.extend([fgear, sil, mavproxy])

Tools/autotest/autotest.py

@@ -94,8 +94,8 @@ steps = [
     'build2560.ArduPlane',
     'build.ArduPlane',
     'defaults.ArduPlane',
-    'logs.ArduPlane',
     'fly.ArduPlane',
+    'logs.ArduPlane',
     'build1280.ArduCopter',
     'build2560.ArduCopter',
     'build.ArduCopter',

Tools/autotest/util.py

@@ -73,6 +73,10 @@ def pexpect_autoclose(p):
 def pexpect_close(p):
     '''close a pexpect child'''
     global close_list
+
+    xvfb_server_num = getattr(p, 'xvfb_server_num', None)
+    if xvfb_server_num is not None:
+        kill_xvfb(xvfb_server_num)
     try:
         p.close()
     except Exception:
@@ -89,12 +93,7 @@ def pexpect_close_all():
     '''close all pexpect children'''
     global close_list
     for p in close_list[:]:
-        try:
-            p.close()
-            time.sleep(1)
-            p.close(Force=True)
-        except Exception:
-            pass
+        pexpect_close(p)
 
 def start_SIL(atype, valgrind=False, wipe=False, CLI=False):
     '''launch a SIL instance'''
@@ -177,3 +176,13 @@ def lock_file(fname):
     except Exception:
         return None
     return f
+
+def kill_xvfb(server_num):
+    '''Xvfb is tricky to kill!'''
+    try:
+        import signal
+        pid = int(open('/tmp/.X%s-lock' % server_num).read().strip())
+        print("Killing Xvfb process %u" % pid)
+        os.kill(pid, signal.SIGINT)
+    except Exception, msg:
+        print("failed to kill Xvfb process - %s" % msg)