Refactoring of the python multiprocessing code to use queues load balancing based on apply_async();

Use the returned result by apply_async() to fetch compile_worker() results and get rid of python queues;
Optimize the threads handling code
Reuse compile threads via self.mp_pool

workspace_tools/toolchains/__init__.py

@@ -28,6 +28,7 @@ from workspace_tools.settings import BUILD_OPTIONS, MBED_ORG_USER
 
 from multiprocessing import Pool, Manager, cpu_count
 from time import sleep
+from pprint import pprint
 
 import workspace_tools.hooks as hooks
 import re
@@ -66,19 +67,16 @@ def print_notify_verbose(event):
     elif event['type'] == 'progress':
         print_notify(event) # standard handle
 
-def compile_worker(jobs):
-    for job in jobs:
-        _, stderr, rc = run_cmd(job['command'], job['work_dir'])
-        
-        job['queue'].put({
-            'code': rc,
-            'output': stderr,
-            'command': job['command'],
-            'source': job['source'],
-            'object': job['object']
-        })
+def compile_worker(job):
+    _, stderr, rc = run_cmd(job['command'], job['work_dir'])
     
-    return True
+    return {
+        'code': rc,
+        'output': stderr,
+        'command': job['command'],
+        'source': job['source'],
+        'object': job['object']
+    }
 
 class Resources:
     def __init__(self, base_path=None):
@@ -236,6 +234,12 @@ class mbedToolchain:
         self.jobs = 1
         
         self.CHROOT = None
+        
+        self.mp_pool = None
+        
+    def __exit__():
+        if self.mp_pool is not None:
+            self.mp_pool.terminate()
 
     def goanna_parse_line(self, line):
         if "analyze" in self.options:
@@ -500,41 +504,27 @@ class mbedToolchain:
             return objects
 
     def compile_queue(self, queue, objects):
-        manager = Manager()
-        q = manager.Queue()
-        
-        groups = []
-        groups_count = int(self.jobs if self.jobs else cpu_count())
-        for i in range(groups_count):
-            groups.append([])
+        jobs_count = int(self.jobs if self.jobs else cpu_count())
+        if self.mp_pool is None or self.mp_pool._state == 2: # TERMINATE
+            self.mp_pool = Pool(processes=jobs_count)
         
+        results = []
         for i in range(len(queue)):
-            queue[i]['queue'] = q
-            g = i % groups_count
-            groups[g].append(queue[i])
-        
-        p = Pool(processes=groups_count)
-        m = p.map_async(compile_worker, groups)
-        
-        done = False
+            results.append(self.mp_pool.apply_async(compile_worker, [queue[i]]))
+
         itr = 0
-
         while True:
-            if itr > 3000:
-                raise ToolException("Compile did not finish in less than 5 minutes")
-            itr = itr + 1
-
-            results = []
-
-            try:
-                while not q.empty():
-                    results.append(q.get())
-            except EOFError:
-                p.terminate()
-                raise ToolException("Failed to spawn child process")
+            itr += 1
+            if itr > 6000:
+                self.mp_pool.terminate()
+                raise ToolException("Compile did not finish in 5 minutes")
             
-            if len(results):
-                for result in results:
+            pending = 0
+            for r in results:
+                if r._ready is True:
+                    result = r.get()
+                    results.remove(r)
+                    
                     objects.append(result['object'])
                     self.compiled += 1
                     self.progress("compile", result['source'], build_update=True)
@@ -546,20 +536,20 @@ class mbedToolchain:
                             result['command']
                         ])
                     except ToolException, err:
-                        p.terminate()
+                        self.mp_pool.terminate()
                         raise ToolException(err)
-            
-            if done:
+                else:
+                    pending += 1
+                    if pending > jobs_count:
+                        break
+                    
+
+            if len(results) == 0:
                 break
 
-            if m.ready(): 
-                done = True
-                #let it run one more time to gather any results left in the queue
-                continue #skip the sleep
-    
-            sleep(0.1)
+            sleep(0.01)
 
-        p.terminate()
+        results = None
         
         return objects