add Callbacks doc #1630
add Callbacks doc #1630
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Thanks @Jasha10 for the great edits. I applied your suggestions and made some minor changes on top :) |
Co-authored-by: Jasha10 <8935917+Jasha10@users.noreply.github.com>
Co-authored-by: Jasha10 <8935917+Jasha10@users.noreply.github.com>
Co-authored-by: Jasha10 <8935917+Jasha10@users.noreply.github.com>
Co-authored-by: Jasha10 <8935917+Jasha10@users.noreply.github.com>
Co-authored-by: Jasha10 <8935917+Jasha10@users.noreply.github.com>
| Say we have `MyCallback` so after every job ends we can upload a certain file to a S3 bucket. | ||
| For simplicity we include this Callback class within the application, in real life you should have the | ||
| Callback in a separate file. | ||
| Running the application, we can see our custom method `on_job_end` was called. |
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This sentence does not read right to me.
Something like this would work better in my opinion:
In this example, we will use a callback to upload a certain file to an S3 bucket at the end of the job.
For simplicity we include this Callback class within the application, real applications are likely to place it in a different Python file.
Running the application, we can see our custom method on_job_end was called.
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| </details> | ||
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| ### Configure Callback |
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This would work better:
### Callback usage example
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| ### Callback ordering |
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### Callback execution order
| The `on_run_start` or `on_multirun_start` method will get called first, | ||
| followed by `on_job_start` (called once for each job). | ||
| After each job `on_job_end` is called, and finally either `on_run_end` or | ||
| `on_multirun_end` is called one time before the application exits. | ||
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| In the `hydra.callbacks` section of your config, you can use a list to register multiple callbacks. They will be called in the final composed order for `start` events and | ||
| in reversed order for `end` events. So, for example, suppose we have the following composed config: | ||
| ```commandline title="python my_app.py --cfg hydra -p hydra.callbacks" | ||
| # @package hydra.callbacks | ||
| my_callback1: | ||
| _target_: my_app.MyCallback1 | ||
| param1: val1 | ||
| my_callback2: | ||
| _target_: my_app.MyCallback2 | ||
| param2: val2 | ||
| ``` | ||
| Before each job starts, `MyCallback1.on_job_start` will get called first, | ||
| followed by `MyCallback2.on_job_start`. | ||
| After each job ends, `MyCallback2.on_job_end` will get called first, | ||
| followed by `MyCallback1.on_job_end`. |
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That's a lot of text to explain something pretty simple:
start events are getting called in order defined in the config and end events are getting called in reverse order.
This can probably be simplified quite a bit.
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Thanks for taking a look omry, i've created #1636 to address the comments. |
Closes #1526