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@@ -182,6 +182,82 @@ Important Notes
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--autoscale=10,3 (always keep 3 processes, but grow to
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10 if necessary).
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+* Remote Debugging of Tasks
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+
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+ ``celery.contrib.rdb`` is an extended version of :mod:`pdb` that
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+ enables remote debugging of processes that does not have terminal
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+ access.
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+
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+ Example usage:
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+
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+ .. code-block:: python
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+
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+ from celery.contrib import rdb
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+ from celery.task import task
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+
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+ @task
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+ def add(x, y):
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+ result = x + y
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+ rdb.set_trace() # <- set breakpoint
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+ return result
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+
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+
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+ :func:`~celery.contrib.rdb.set_trace` sets a breakpoint at the current
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+ location and creates a socket you can telnet into to remotely debug
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+ your task.
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+
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+ The debugger may be started by multiple processes at the same time,
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+ so rather than using a fixed port the debugger will search for an
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+ available port, starting from the base port (6900 by default).
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+ The base port can be changed using the environment variable
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+ :envvar:`CELERY_RDB_PORT`.
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+
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+ By default the debugger will only be available from the local host,
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+ to enable access from the outside you have to set the environment
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+ variable :envvar:`CELERY_RDB_HOST`.
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+
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+ When `celeryd` encounters your breakpoint it will log the following
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+ information::
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+
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+ [INFO/MainProcess] Got task from broker:
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+ tasks.add[d7261c71-4962-47e5-b342-2448bedd20e8]
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+ [WARNING/PoolWorker-1] Remote Debugger:6900:
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+ Please telnet 127.0.0.1 6900. Type `exit` in session to continue.
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+ [2011-01-18 14:25:44,119: WARNING/PoolWorker-1] Remote Debugger:6900:
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+ Waiting for client...
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+
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+ If you telnet the port specified you will be presented
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+ with a ``pdb`` shell::
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+
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+ $ telnet localhost 6900
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+ Connected to localhost.
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+ Escape character is '^]'.
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+ > /opt/devel/demoapp/tasks.py(128)add()
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+ -> return result
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+ (Pdb)
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+
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+ Enter ``help`` to get a list of available commands,
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+ It may be a good idea to read the `The Python Debugger`_ manual if
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+ you have never used `pdb` before.
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+
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+ To demonstrate, we will read the value of the ``result`` variable,
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+ change it and continue execution of the task::
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+
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+ (Pdb) result
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+ 4
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+ (Pdb) result = "hello from rdb"
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+ (Pdb) continue
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+ Connection closed by foreign host.
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+
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+ The result of our vandalism can be seen in the worker logs::
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+
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+ [2011-01-18 14:35:36,599: INFO/MainProcess] Task
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+ tasks.add[d7261c71-4962-47e5-b342-2448bedd20e8] succeeded
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+ in 61.481s: 'hello from rdb'
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+
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+.. _`The Python Debugger`: http://docs.python.org/library/pdb.html
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+
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+
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* Events are now transient and is using a topic exchange (instead of direct).
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The `CELERYD_EVENT_EXCHANGE`, `CELERYD_EVENT_ROUTING_KEY`,
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