bitbake: cooker: Handle parse threads disappearing to avoid hangs

If one of the parse threads disappears during parsing for some reason, bitbake
currently hangs. Avoid this (and zombie threads hanging around) by joining()
threads which have exited.

(Bitbake rev: 6e746ccf8977a78f1565c6b2fe65aaede260e1bb)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit dc86a533d951d13643ce446533370da804782afc)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/cooker.py

@@ -2036,6 +2036,7 @@ class Parser(multiprocessing.Process):
                 result = pending.pop()
             else:
                 try:
+                    time.sleep(0.25)
                     job = self.jobs.pop()
                 except IndexError:
                     self.results.close()
@@ -2214,7 +2215,7 @@ class CookerParser(object):
             yield not cached, mc, infos
 
     def parse_generator(self):
-        while True:
+        while self.processes:
             if self.parsed >= self.toparse:
                 break
 
@@ -2228,6 +2229,14 @@ class CookerParser(object):
                     raise value
                 else:
                     yield result
+            for process in self.processes.copy():
+                if not process.is_alive():
+                    process.join()
+                    self.processes.remove(process)
+
+        if not (self.parsed >= self.toparse):
+            raise bb.parse.ParseError("Not all recipes parsed, parser thread killed/died? Exiting.", None)
+
 
     def parse_next(self):
         result = []