Resolve parsing hang issues

index bb09dff..8188aae 100644
@@ -36,6 +36,7 @@ from functools import wraps
 from collections import defaultdict
 import bb, bb.exceptions, bb.command
 from bb import utils, data, parse, event, cache, providers, taskdata, runqueue
+import Queue
 import prserv.serv
 
 logger      = logging.getLogger("BitBake")

@@ -1402,20 +1403,87 @@ class ParsingFailure(Exception):
         self.recipe = recipe
         Exception.__init__(self, realexception, recipe)
 
-def parse_file(task):
-    filename, appends, caches_array = task
-    try:
-        return True, bb.cache.Cache.parse(filename, appends, parse_file.cfg, caches_array)
-    except Exception as exc:
-        tb = sys.exc_info()[2]
-        exc.recipe = filename
-        exc.traceback = list(bb.exceptions.extract_traceback(tb, context=3))
-        raise exc
-    # Need to turn BaseExceptions into Exceptions here so we gracefully shutdown
-    # and for example a worker thread doesn't just exit on its own in response to
-    # a SystemExit event for example.
-    except BaseException as exc:
-        raise ParsingFailure(exc, filename)
+class Feeder(multiprocessing.Process):
+    def __init__(self, jobs, to_parsers, quit):
+        self.quit = quit
+        self.jobs = jobs
+        self.to_parsers = to_parsers
+        multiprocessing.Process.__init__(self)
+
+    def run(self):
+        while True:
+            try:
+                quit = self.quit.get_nowait()
+            except Queue.Empty:
+                pass
+            else:
+                if quit == 'cancel':
+                    self.to_parsers.cancel_join_thread()
+                break
+
+            try:
+                job = self.jobs.pop()
+            except IndexError:
+                break
+
+            try:
+                self.to_parsers.put(job, timeout=0.5)
+            except Queue.Full:
+                self.jobs.insert(0, job)
+                continue
+
+class Parser(multiprocessing.Process):
+    def __init__(self, jobs, results, quit, init):
+        self.jobs = jobs
+        self.results = results
+        self.quit = quit
+        self.init = init
+        multiprocessing.Process.__init__(self)
+
+    def run(self):
+        if self.init:
+            self.init()
+
+        pending = []
+        while True:
+            try:
+                self.quit.get_nowait()
+            except Queue.Empty:
+                pass
+            else:
+                self.results.cancel_join_thread()
+                break
+
+            if pending:
+                result = pending.pop()
+            else:
+                try:
+                    job = self.jobs.get(timeout=0.25)
+                except Queue.Empty:
+                    continue
+
+                if job is None:
+                    break
+                result = self.parse(*job)
+
+            try:
+                self.results.put(result, timeout=0.25)
+            except Queue.Full:
+                pending.append(result)
+
+    def parse(self, filename, appends, caches_array):
+        try:
+            return True, bb.cache.Cache.parse(filename, appends, self.cfg, caches_array)
+        except Exception as exc:
+            tb = sys.exc_info()[2]
+            exc.recipe = filename
+            exc.traceback = list(bb.exceptions.extract_traceback(tb, context=3))
+            return True, exc
+        # Need to turn BaseExceptions into Exceptions here so we gracefully shutdown
+        # and for example a worker thread doesn't just exit on its own in response to
+        # a SystemExit event for example.
+        except BaseException as exc:
+            return True, ParsingFailure(exc, filename)
 
 class CookerParser(object):
     def __init__(self, cooker, filelist, masked):

@@ -1452,22 +1520,28 @@ class CookerParser(object):
         self.start()
 
     def start(self):
-        def init(cfg):
-            parse_file.cfg = cfg
-            multiprocessing.util.Finalize(None, bb.codeparser.parser_cache_save, args=(self.cooker.configuration.data, ), exitpriority=1)
-
         self.results = self.load_cached()
-
+        self.processes = []
         if self.toparse:
             bb.event.fire(bb.event.ParseStarted(self.toparse), self.cfgdata)
+            def init():
+                Parser.cfg = self.cfgdata
+                multiprocessing.util.Finalize(None, bb.codeparser.parser_cache_save, args=(self.cfgdata,), exitpriority=1)
 
-            self.pool = multiprocessing.Pool(self.num_processes, init, [self.cfgdata])
-            parsed = self.pool.imap(parse_file, self.willparse)
-            self.pool.close()
+            self.feeder_quit = multiprocessing.Queue(maxsize=1)
+            self.parser_quit = multiprocessing.Queue(maxsize=self.num_processes)
+            self.jobs = multiprocessing.Queue(maxsize=self.num_processes)
+            self.result_queue = multiprocessing.Queue()
+            self.feeder = Feeder(self.willparse, self.jobs, self.feeder_quit)
+            self.feeder.start()
+            for i in range(1, self.num_processes):
+                parser = Parser(self.jobs, self.result_queue, self.parser_quit, init)
+                parser.start()
+                self.processes.append(parser)
 
-            self.results = itertools.chain(self.results, parsed)
+            self.results = itertools.chain(self.results, self.parse_generator())
 
-    def shutdown(self, clean=True):
+    def shutdown(self, clean=True, force=False):
         if not self.toparse:
             return
 

@@ -1477,9 +1551,22 @@ class CookerParser(object):
                                             self.virtuals, self.error,
                                             self.total)
             bb.event.fire(event, self.cfgdata)
+            self.feeder_quit.put(None)
+            for process in self.processes:
+                self.jobs.put(None)
         else:
-            self.pool.terminate()
-        self.pool.join()
+            self.feeder_quit.put('cancel')
+
+            self.parser_quit.cancel_join_thread()
+            for process in self.processes:
+                self.parser_quit.put(None)
+
+            self.jobs.cancel_join_thread()
+            sys.exit(1)
+
+        for process in self.processes:
+            process.join()
+        self.feeder.join()
 
         sync = threading.Thread(target=self.bb_cache.sync)
         sync.start()

@@ -1491,6 +1578,22 @@ class CookerParser(object):
             cached, infos = self.bb_cache.load(filename, appends, self.cfgdata)
             yield not cached, infos
 
+    def parse_generator(self):
+        while True:
+            if self.parsed >= self.toparse:
+                break
+
+            try:
+                result = self.result_queue.get(timeout=0.25)
+            except Queue.Empty:
+                pass
+            else:
+                value = result[1]
+                if isinstance(value, BaseException):
+                    raise value
+                else:
+                    yield result
+
     def parse_next(self):
         try:
             parsed, result = self.results.next()

index e1d42f7..22370ef 100644
@@ -118,6 +118,8 @@ def main(server, eventHandler):
         try:
             event = eventHandler.waitEvent(0.25)
             if event is None:
+                if shutdown > 1:
+                    break
                 continue
             helper.eventHandler(event)
             if isinstance(event, bb.runqueue.runQueueExitWait):

@@ -199,18 +201,18 @@ def main(server, eventHandler):
                 print("Loaded %d entries from dependency cache." % event.num_entries)
                 continue
 
-            if isinstance(event, bb.command.CommandCompleted):
-                break
             if isinstance(event, bb.command.CommandFailed):
                 return_value = event.exitcode
                 logger.error("Command execution failed: %s", event.error)
-                break
+                shutdown = 2
+                continue
             if isinstance(event, bb.command.CommandExit):
                 if not return_value:
                     return_value = event.exitcode
                 continue
-            if isinstance(event, bb.cooker.CookerExit):
-                break
+            if isinstance(event, (bb.command.CommandCompleted, bb.cooker.CookerExit)):
+                shutdown = 2
+                continue
             if isinstance(event, bb.event.MultipleProviders):
                 logger.info("multiple providers are available for %s%s (%s)", event._is_runtime and "runtime " or "",
                             event._item,

@@ -269,9 +271,6 @@ def main(server, eventHandler):
             if ioerror.args[0] == 4:
                 pass
         except KeyboardInterrupt:
-            if shutdown == 2:
-                print("\nThird Keyboard Interrupt, exit.\n")
-                break
             if shutdown == 1:
                 print("\nSecond Keyboard Interrupt, stopping...\n")
                 server.runCommand(["stateStop"])