[PATCH] runqueue.py: Handle worker disappearing gracefully

[Richard Purdie <richard.purdie@linuxfoundation.org>]

If the worker (or fakeworker) process disappears for some reason, the
system doesn't currently even notice. To fix this, we call waitpid
periodically, looking for exit events of our children. If these
occur, we can gracefully shutdown the server.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
diff --git a/bitbake/lib/bb/runqueue.py b/bitbake/lib/bb/runqueue.py
index 241e387..967e944 100644
--- a/bitbake/lib/bb/runqueue.py
+++ b/bitbake/lib/bb/runqueue.py
@@ -869,7 +869,7 @@ class RunQueue:
         else:
             worker = subprocess.Popen(["bitbake-worker", "decafbad"], stdout=subprocess.PIPE, stdin=subprocess.PIPE)
         bb.utils.nonblockingfd(worker.stdout)
-        workerpipe = runQueuePipe(worker.stdout, None, self.cfgData, rqexec)
+        workerpipe = runQueuePipe(worker.stdout, None, self.cfgData, self, rqexec)
 
         workerdata = {
             "taskdeps" : self.rqdata.dataCache.task_deps,
@@ -912,6 +912,7 @@ class RunQueue:
     def start_worker(self):
         if self.worker:
             self.teardown_workers()
+        self.teardown = False
         self.worker, self.workerpipe = self._start_worker()
 
     def start_fakeworker(self, rqexec):
@@ -919,6 +920,7 @@ class RunQueue:
             self.fakeworker, self.fakeworkerpipe = self._start_worker(True, rqexec)
 
     def teardown_workers(self):
+        self.teardown = True
         self._teardown_worker(self.worker, self.workerpipe)
         self.worker = None
         self.workerpipe = None
@@ -2067,7 +2069,7 @@ class runQueuePipe():
     """
     Abstraction for a pipe between a worker thread and the server
     """
-    def __init__(self, pipein, pipeout, d, rq):
+    def __init__(self, pipein, pipeout, d, rq, rqexec):
         self.input = pipein
         if pipeout:
             pipeout.close()
@@ -2075,11 +2077,26 @@ class runQueuePipe():
         self.queue = ""
         self.d = d
         self.rq = rq
+        self.rqexec = rqexec
 
-    def setrunqueueexec(self, rq):
-        self.rq = rq
+    def setrunqueueexec(self, rqexec):
+        self.rqexec = rqexec
 
     def read(self):
+        try:
+            pid, status = os.waitpid(-1, os.WNOHANG)
+            if pid != 0 and not self.rq.teardown:
+                if self.rq.worker and pid == self.rq.worker.pid:
+                    name = "Worker"
+                elif self.rq.fakeworker and pid == self.rq.fakeworker.pid:
+                    name = "Fakeroot"
+                else:
+                    name = "Unknown"
+                bb.error("%s process (%s) exited unexpectedly (%s), shutting down..." % (name, pid, str(status)))
+                self.rq.finish_runqueue(True)
+        except OSError:
+            pass
+
         start = len(self.queue)
         try:
             self.queue = self.queue + self.input.read(102400)
@@ -2106,7 +2123,7 @@ class runQueuePipe():
                     task, status = pickle.loads(self.queue[10:index])
                 except ValueError as e:
                     bb.msg.fatal("RunQueue", "failed load pickle '%s': '%s'" % (e, self.queue[10:index]))
-                self.rq.runqueue_process_waitpid(task, status)
+                self.rqexec.runqueue_process_waitpid(task, status)
                 found = True
                 self.queue = self.queue[index+11:]
                 index = self.queue.find("</exitcode>")