Refactor job processing app to do actual job queue and job subprocess launching, remove queue mananger app, update ocr app to use new job processing app

apps/job_processor/tasks.py

@@ -0,0 +1,58 @@
+from __future__ import absolute_import
+
+from datetime import timedelta, datetime
+import platform
+import logging
+import psutil
+
+from lock_manager import Lock, LockError
+
+from .models import Node, JobQueue
+from .exceptions import JobQueueNoPendingJobs
+
+LOCK_EXPIRE = 10
+# TODO: Tie LOCK_EXPIRATION with hard task timeout
+
+logger = logging.getLogger(__name__)
+
+
+def refresh_node():
+    logger.debug('starting')
+
+    lock_id = u'refresh_node'
+    try:
+        logger.debug('trying to acquire lock: %s' % lock_id)
+        lock = Lock.acquire_lock(lock_id, LOCK_EXPIRE)
+        logger.debug('acquired lock: %s' % lock_id)
+        node, created = Node.objects.get_or_create(hostname=platform.node(), defaults={'memory_usage': 0.0})
+        node.cpuload = psutil.cpu_percent()
+        node.memory_usage = psutil.phymem_usage().percent
+        node.save()
+        lock.release()
+    except LockError:
+        logger.debug('unable to obtain lock')
+    except Exception:
+        lock.release()
+        raise
+
+
+def job_queue_poll():
+    logger.debug('starting')
+
+    lock_id = u'job_queue_poll'
+    try:
+        logger.debug('trying to acquire lock: %s' % lock_id)
+        lock = Lock.acquire_lock(lock_id, LOCK_EXPIRE)
+        logger.debug('acquired lock: %s' % lock_id)
+        for job_queue in JobQueue.objects.all():
+            try:
+                job_item = job_queue.get_oldest_pending_job()
+                job_item.run()
+            except JobQueueNoPendingJobs:
+                logger.debug('no pending jobs for job queue: %s' % job_queue)
+        lock.release()
+    except LockError:
+        logger.debug('unable to obtain lock')
+    except Exception:
+        lock.release()
+        raise