Minor tweaks

Author: mdbenito

docs/getting-started/advanced-usage.md

@@ -57,7 +57,7 @@ parallel_backend = init_parallel_backend(backend_name="joblib")
     of pyDVL. They are used internally as part of the computations of the 
     different methods.
 
-!!! info
+!!! danger "Deprecation notice"
 
     We are currently planning to deprecate
     [MapReduceJob][pydvl.parallel.map_reduce.MapReduceJob] in favour of the
@@ -88,7 +88,7 @@ with joblib.parallel_config(backend="loky", verbose=100):
 
 #### Ray
 
-!!! info
+!!! warning "Additional dependencies"
 
     The Ray parallel backend requires optional dependencies.
     See [Extras][installation-extras] for more information.
@@ -155,13 +155,13 @@ classes.
 [1, 2, 3]
 ```
 
-#### Map reduce
+#### Map-reduce
 
-The map reduce interface is older and more limited in the patterns
+The map-reduce interface is older and more limited in the patterns
 it allows us to use.
 
 To reproduce the previous example using
-[MapReduceJob][pydvl.parallel.map_reduce.MapReduceJob]we would use:
+[MapReduceJob][pydvl.parallel.map_reduce.MapReduceJob], we would use:
 
 ```pycon
 >>> from pydvl.parallel import JoblibParallelBackend, MapReduceJob

src/pydvl/parallel/__init__.py

@@ -27,7 +27,18 @@
     results = list(executor.map(lambda x: x + 1, range(5)))
 assert results == [1, 2, 3, 4, 5]
 ```
-
+!!! tip "Passsing large objects"
+    When running tasks which accept heavy inputs, it is important
+    to first use `put()` on the object and use the returned reference
+    as argument to the callable within `submit()`. For example:    
+    ```python
+    u_ref = parallel_backend.put(u)
+    ...
+    executor.submit(task, utility=u)
+    ```
+    Note that `task()` does not need to be changed in any way:
+    the backend will `get()` the object and pass it to the function
+    upon invocation.
 There is an alternative map-reduce implementation
 [MapReduceJob][pydvl.parallel.map_reduce.MapReduceJob] which internally
 uses joblib's higher level API with `Parallel()` which then indirectly also