Diferencias

Muestra las diferencias entre dos versiones de la página.

--- fw:celery [2014/08/17 15:06]
alfred [Routing]
+++ fw:celery [2020/05/09 09:25] (actual)
@@ Línea 393: / Línea 393: @@
 ==== Application ====
 ==== Tasks ====
+A task message does not disappear from a queue until it has been acknowldged by a worker. If the worker is kile the message will be redelivered to ntoher worker. It acknowledge the message in advance, before it's executed (the task that has already been starte is never executed again). However you can set the acks_late option to have the worker acknowledge the message after the task returns instead. \\
+You create a task using the ''@task'' decorator. If you needed to use more decorator, this should be the first:
+<code python>
+@app.task
+@decorator2
+@decorator1
+def add(x, y):
+    return x + y
+</code>
+A name of a task is generated from the name of the function. If you wanted to assign another name you should use the name parameter for the ''@task'' decorator. A best practice is to use the module name as a namespace, this way names won’t collide:
+<code python>
+@app.task(name='tasks.add')
+def add(x, y):
+  return x + y
+</code>
+You can know the name of the task using the ''name'' property:
+<code>
+add.name
+</code>
+The bind parameter for ''@task'' allows to the task to recibe information of its calling using the [[http://docs.celeryproject.org/en/latest/userguide/tasks.html#context|request variable]]. The data is accessed in the ''self'' variable. \\
+You can also use the ''.retry()'' method to send the same task again. This method cuts the execution of the task, it's because it throws an exception. If you don't want this behaviour set the ''throw'' parameter for ''retry()'' as ''False''. There also is the ''max_retries'' properties. Or the ''default_retry_delay'' for the task (default set as 30 secs).
+<code python>
+@app.task(bind=True)
+def send_twitter_status(self, oauth, tweet):
+    try:
+        twitter = Twitter(oauth)
+        twitter.update_status(tweet)
+    except (Twitter.FailWhaleError, Twitter.LoginError) as exc:
+        raise self.retry(exc=exc)
+</code>
+  * More [[options for tasks]].
+  * If you don’t care about the results of a task, be sure to set the ignore_result option, as storing results wastes time and resources.
+  * Disabling rate limits altogether is recommended if you don’t have any tasks using them. This is because the rate limit subsystem introduces quite a lot of complexity (with ''CELERY_DISABLE_RATE_LIMITS'' variable set as ''True'').
 ==== Routing ====
 Option ''CELERY_CREATE_MISSING_QUEUES'' setted as ''True'' will allow Celery to autoconfigure queues by default.  Default queue is named ''celery''. To change it you will use:
@@ Línea 507: / Línea 540: @@
 ==== Testing ====
 With the configuration ''CELERY_ALWAYS_EAGER'' assigned as True, all the workers are called without any asynchronous behavior.
+==== Periodic tasks ====
+You can call Celery tasks in concrete moments: [[http://docs.celeryproject.org/en/latest/userguide/periodic-tasks.html| periodic tasks guide]]. To do so you need a beat process (only one) to call the workers when it's needed. Next example are two files:
+  * **beat.py**, which is executed as: ''celery -A beat beat''
+<code python>
+from datetime import timedelta
+from celery import Celery
+from tasks import app
+app.conf.update(
+		CELERYBEAT_SCHEDULE = {
+		    'add-every-30-seconds': {
+		        'task': 'tasks.add',
+		        'schedule': timedelta(seconds=10)
+		    },
+		},
+		CELERY_TIMEZONE = 'UTC'
+	)
+</code>
+  * **tasks.py**, which is executed as: ''celery -A tasks worker''
+<code python>
+from celery import Celery
+import datetime
+app = Celery('tasks', broker='amqp://guest@192.168.0.100//')
+@app.task
+def add():
+    f = open('/home/alfred/a.txt', 'a')
+    f.write(str(datetime.datetime.now()))
+    f.close()
+</code>
 ==== Little tools ====
-=== Periodic tasks ===
-You can call Celery tasks in concrete moments: [[http://docs.celeryproject.org/en/latest/userguide/periodic-tasks.html| periodic tasks guide]].
 === HTTP Callbacks ===
@@ Línea 612: / Línea 676: @@
 $ python manage.py celeryd -l info
 </code>
+==== Notes ====
+  * If you want to use print you must set ''CELERY_REDIRECT_STDOUTS'' to ''False''.
+=== Execute celery task from c# ===
+<code csharp>
+using (var channel = connection.CreateModel())
+{
+    var guid = Guid.NewGuid().ToString();
+    string message = String.Format("{{\"id\": \"{0}\", \"task\": \"my.task\", \"args\": [1, 2]}}",  guid);
+    var body = Encoding.UTF8.GetBytes(message);
+    IBasicProperties props = channel.CreateBasicProperties();
+    props.ContentType = "application/json";
+    props.ContentEncoding = "UTF-8";
+    //channel.QueueDeclare("celery", true, true, false, null);
+    channel.BasicPublish("celery", "celery", props, body);
+    Console.WriteLine(" [x] Sent {0}", message);
+}
+</code>
+When task is:
+<code python>
+app = Celery('tasks', broker='amqp://guest@192.168.0.100//')
+@app.task(name='my.task', ignore_result=True)
+def add(a, b):
+    logger = get_task_logger(__name__)
+    logger.critical('tralara lalala ' + str(a+b))
+</code>

Programming

Herramientas de usuario

Herramientas del sitio

Diferencias

Herramientas de la página