process-based worker

oshipka/webapp/async_routes.py

@@ -1,18 +1,16 @@
-import itertools
 import json
 import os
 import subprocess
 import time
 from uuid import uuid4
 
+from config import TASKS_BUF_DIR
 from flask import render_template, request, Response, redirect, url_for, jsonify
 from flask_table import Table, LinkCol, Col
 
 from oshipka.persistance import db
 from oshipka.webapp import test_bp, oshipka_bp
 
-from config import TASKS_BUF_DIR
-
 TASKS = {}
 
 
@@ -20,17 +18,8 @@ def register_task(task_name, task_func, *args, **kwargs):
     TASKS[task_name] = task_func
 
 
-def stateless_task():
-    for i, c in enumerate(itertools.cycle('\|/-')):
-        yield "data: %s %d\n\n" % (c, i)
-        time.sleep(.1)  # an artificial delay
-
-
-register_task("stateless_task", stateless_task)
-
-
 def stateful_task(*args, **kwargs):
-    n = 100
+    n = 5
     for i in range(0, n + 1):
         print(i)
         time.sleep(1)
@@ -79,9 +68,7 @@ def tail(filename):
                                )
     for line in iter(process.stdout.readline, b''):
         line = line.strip()
-        # print("sending s_tail: {}".format(line))
         yield "data: {}\n\n".format(line)
-        # print("sent s_tail: {}".format((line)))
 
 
 def worker_start_task(task_name, func_name, task_kwargs):
@@ -127,6 +114,5 @@ def stream(task_uuid):
         task = Task.query.filter_by(uuid=task_uuid).first()
         if not task:
             return jsonify({"error": "no task with uuid {}".format(task_uuid)}), 404
-        # return Response(stateless_task(), content_type='text/event-stream')
         return Response(tail(os.path.join(TASKS_BUF_DIR, task_uuid)), content_type='text/event-stream')
     return jsonify({"error": "Request has to contain 'Accept: text/event-stream' header"}), 400

oshipka/worker.py

@@ -1,20 +1,25 @@
 import json
+import multiprocessing
 import os
 import queue
 import signal
+import time
+
 import sys
 import threading
+from copy import deepcopy
 from importlib import import_module
 from time import sleep
 
+from filelock import FileLock, Timeout
+
 from oshipka.persistance import init_db, db
 from oshipka.webapp import app
 from oshipka.webapp.async_routes import Task
+from watchdog.observers import Observer
+from watchdog.events import FileSystemEventHandler
 
-from config import TASKS_BUF_DIR
-
-q = queue.Queue()
-POISON_PILL = "-.-.-.-"
+from config import TASKS_BUF_DIR, TASKS_IN_DIR
 
 
 def dyn_import(name):
@@ -42,47 +47,97 @@ class Unbuffered(object):
         return getattr(self.stream, attr)
 
 
+class DirectoryWatcherHandler(FileSystemEventHandler):
+    def __init__(self, worker):
+        self.worker = worker
+
+    def on_any_event(self, event):
+        if event.is_directory:
+            return None
+
+        elif event.event_type == 'created':
+            # Take any action here when a file is first created.
+            task_uuid = os.path.basename(event.src_path)
+            if task_uuid.endswith(".lock"):
+                return
+            lock_fname = os.path.join(TASKS_IN_DIR, task_uuid)
+            lock = FileLock("{}.lock".format(lock_fname))
+            try:
+                with lock.acquire(timeout=1):
+                    print("WATCHER: Acquired lock for {}.".format(task_uuid))
+                    with open(lock_fname, 'r') as f:
+                        if f.read() == "processing":
+                            return
+                    open(lock_fname, "w").write("processing")
+                    self.worker.process(task_uuid)
+                    open(lock_fname, "w").write("done")
+                    os.remove(lock_fname)
+                    print("WATCHER: Released lock for {}.".format(task_uuid))
+            except Timeout as e:
+                return
+            except Exception as e:
+                print("WATCHER: Exception: {}".format(e))
+            finally:
+                lock.release()
+
+
+class DirectoryWatcher(object):
+    def __init__(self, worker):
+        self.worker = worker
+        self.observer = Observer()
+        self.event_handler = DirectoryWatcherHandler(self.worker)
+
+    def run(self):
+        self.observer.schedule(self.event_handler, self.worker.directory, recursive=True)
+        self.observer.start()
+        try:
+            while RUNNING:
+                time.sleep(3)
+            print("DirectoryWatcher: Stopped")
+        except:
+            print("DirectoryWatcher: Error")
+        self.observer.stop()
+        self.observer.join()
+
+
 class Worker(object):
-    def __init__(self):
-        self.stored_sys_stdout = None
-        self.stored_sys_stderr = None
+    def __init__(self, tasks_dir):
+        self.worker_name = None
+        self.directory = tasks_dir
+        self.watcher = DirectoryWatcher(self)
 
     def before_task(self, task_uuid):
-        self.stored_sys_stdout = sys.stdout
-        self.stored_sys_stdout = sys.stdout
-
         sys.stdout = Unbuffered(open(os.path.join(TASKS_BUF_DIR, task_uuid), 'w'))
         sys.stderr = Unbuffered(open(os.path.join(TASKS_BUF_DIR, task_uuid), 'w'))
 
     def after_task(self, task_uuid):
-        sys.stdout = self.stored_sys_stdout
-        sys.stdout = self.stored_sys_stderr
+        sys.stdout = sys.__stdout__
+        sys.stderr = sys.__stderr__
 
     def start(self):
+        worker_id = multiprocessing.current_process()
+        self.worker_name = worker_id.name
+
+        print("Started worker {} (pid: {})".format(self.worker_name, worker_id.pid))
+        self.watcher.run()
+
+    def process(self, task_uuid):
         app.app_context().push()
         app.test_request_context().push()
 
-        worker_id = threading.get_ident()
-        print("Started worker {}".format(worker_id))
-        while True:
-            print("Worker {} waiting for tasks...".format(worker_id))
-            task_uuid = q.get()
-            if task_uuid == POISON_PILL:
-                print("Killing worker {}".format(worker_id))
-                break
         task = Task.query.filter_by(uuid=task_uuid).first()
-            print("Worker {} received task: {}".format(worker_id, task.name))
+        print("Worker {} received task: {}".format(self.worker_name, task.name))
 
         task.status = "STARTED"
         db.session.add(task)
         db.session.commit()
 
-            print("Worker {} started task: {}".format(worker_id, task.name))
+        print("Worker {} started task: {}".format(self.worker_name, task.name))
         task_func = dyn_import(task.func_name)
         self.before_task(task.uuid)
         task_func(*json.loads(task.args), **json.loads(task.kwargs))
         self.after_task(task.uuid)
-            print("Worker {} finished task: {}".format(worker_id, task.name))
+        print("Worker {} finished task: {}".format(self.worker_name, task.name))
 
         task.status = "DONE"
         db.session.add(task)
@@ -106,11 +161,11 @@ def main(workers_cnt=4):
     app.test_request_context().push()
     init_db(app)
 
-    thread_pool = []
+    worker_pool = []
     for w in range(workers_cnt):
-        worker = Worker()
-        t = threading.Thread(target=worker.start, args=())
-        thread_pool.append(t)
+        worker = Worker(TASKS_IN_DIR)
+        t = multiprocessing.Process(target=worker.start, args=())
+        worker_pool.append(t)
         t.start()
 
     print("Started main loop")
@@ -118,17 +173,19 @@ def main(workers_cnt=4):
     while RUNNING:
         not_started_tasks = Task.query.filter_by(status="NOT_STARTED").all()
         for task in not_started_tasks:
+            lock_fname = os.path.join(TASKS_IN_DIR, task.uuid)
+            lock = FileLock("{}.lock".format(lock_fname))
+            with lock:
+                open(lock_fname, "a").write("queued")
+
             task.status = "QUEUED"
             db.session.add(task)
             db.session.commit()
 
-            q.put(task.uuid)
-
         sleep(1)
 
     print("exiting main loop")
-    for t in thread_pool:
-        q.put(POISON_PILL)
+    for t in worker_pool:
         t.join()
 
 

requirements.txt

@@ -1,9 +1,12 @@
 click==7.1.1
+filelock==3.0.12
 Flask==1.1.1
 Flask-SQLAlchemy==2.4.1
 itsdangerous==1.1.0
 Jinja2==2.11.1
 MarkupSafe==1.1.1
+pathtools==0.1.2
 pkg-resources==0.0.0
 SQLAlchemy==1.3.15
+watchdog==0.10.2
 Werkzeug==1.0.0