Use setproctitle if avaiable to show state

setproctitle() changes the process name, particularly in top/ps output
on posix-y systems.  This is very useful to get some transparency on
what's going on, especially if a test starts taking a very long time or
straight up hangs.

This is strictly a "bonus goodie", if setproctitle is not available,
it's not used, and any errors are ignored silently.

Signed-off-by: David Lamparter <equinox@diac24.net>

changelog/696.feature.rst

@@ -0,0 +1,2 @@
+Use setproctitle() to indicate current worker state if correspondent package
+is available.  Absent package (or any errors) just continues unchanged.

src/xdist/remote.py

@@ -16,6 +16,21 @@
 
 from _pytest.config import _prepareconfig, Config
 
+try:
+    from setproctitle import setproctitle
+except ImportError:
+
+    def setproctitle(title):
+        pass
+
+
+def worker_title(title):
+    try:
+        setproctitle(title)
+    except Exception:
+        # changing the process name is very optional, no errors please
+        pass
+
 
 class WorkerInteractor:
     def __init__(self, config, channel):
@@ -85,9 +100,14 @@ def run_one_test(self, torun):
         else:
             nextitem = None
 
+        worker_title("[pytest-xdist running] %s" % item.nodeid)
+
         start = time.time()
         self.config.hook.pytest_runtest_protocol(item=item, nextitem=nextitem)
         duration = time.time() - start
+
+        worker_title("[pytest-xdist idle]")
+
         self.sendevent(
             "runtest_protocol_complete", item_index=self.item_index, duration=duration
         )