Libensemble · jlnav · May 2, 2025 · May 2, 2025 · May 2, 2025 · May 2, 2025
diff --git a/docs/FAQ.rst b/docs/FAQ.rst
@@ -13,11 +13,6 @@ We recommend using the following options to help debug workflows::
     logger.set_level("DEBUG")
     libE_specs["safe_mode"] = True
 
-To make it easier to debug a generator try setting the **libE_specs** option ``gen_on_manager``.
-To do so, add the following to your calling script::
-
-    libE_specs["gen_on_manager"] = True
-
 With this, ``pdb`` breakpoints can be set as usual in the generator.
 
 For more debugging options see "How can I debug specific libEnsemble processes?" below.

diff --git a/docs/data_structures/libE_specs.rst b/docs/data_structures/libE_specs.rst
@@ -9,12 +9,7 @@ libEnsemble is primarily customized by setting options within a ``LibeSpecs`` cl
 
     from libensemble.specs import LibeSpecs
 
-    specs = LibeSpecs(
-        gen_on_manager=True,
-        save_every_k_gens=100,
-        sim_dirs_make=True,
-        nworkers=4
-    )
+    specs = LibeSpecs(save_every_k_gens=100, sim_dirs_make=True, nworkers=4)
 
 .. dropdown:: Settings by Category
     :open:
@@ -31,9 +26,8 @@ libEnsemble is primarily customized by setting options within a ``LibeSpecs`` cl
                 **nworkers** [int]:
                     Number of worker processes in ``"local"``, ``"threads"``, or ``"tcp"``.
 
-                **gen_on_manager** [bool] = False
-                    Instructs Manager process to run generator functions.
-                    This generator function can access/modify user objects by reference.
+                **gen_on_worker** [bool] = False
+                    Instructs Worker process to run generator instead of Manager.
 
                 **mpi_comm** [MPI communicator] = ``MPI.COMM_WORLD``:
                     libEnsemble MPI communicator.

diff --git a/docs/overview_usecases.rst b/docs/overview_usecases.rst
@@ -20,6 +20,9 @@ which perform computations via **user functions**:
 
 |
 
+As of **v2.0** the **Manager** by default runs **a single generator**. This
+is configurable.
+
 The default allocator (``alloc_f``) instructs workers to run the simulator on the
 highest priority work from the generator. If a worker is idle and there is
 no work, that worker is instructed to call the generator.

diff --git a/docs/platforms/aurora.rst b/docs/platforms/aurora.rst
@@ -57,7 +57,7 @@ simulations for each worker:
 .. code-block:: python
 
     # Instruct libEnsemble to exit after this many simulations
-    ensemble.exit_criteria = ExitCriteria(sim_max=nsim_workers*2)
+    ensemble.exit_criteria = ExitCriteria(sim_max=nsim_workers * 2)
 
 Now grab an interactive session on two nodes (or use the batch script at
 ``../submission_scripts/submit_pbs_aurora.sh``)::
@@ -115,26 +115,6 @@ will use one GPU tile)::
 
     python run_libe_forces.py -n 25
 
-Running generator on the manager
---------------------------------
-
-An alternative is to run the generator on a thread on the manager. The
-number of workers can then be set to the number of simulation workers.
-
-Change the ``libE_specs`` in **run_libe_forces.py** as follows:
-
-.. code-block:: python
-
-    nsim_workers = ensemble.nworkers
-
-    # Persistent gen does not need resources
-    ensemble.libE_specs = LibeSpecs(
-        gen_on_manager=True,
-
-then we can run with 12 (instead of 13) workers::
-
-    python run_libe_forces.py -n 12
-
 Dynamic resource assignment
 ---------------------------
 

diff --git a/docs/platforms/perlmutter.rst b/docs/platforms/perlmutter.rst
@@ -105,26 +105,6 @@ To see GPU usage, ssh into the node you are on in another window and run::
 
     watch -n 0.1 nvidia-smi
 
-Running generator on the manager
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-An alternative is to run the generator on a thread on the manager. The
-number of workers can then be set to the number of simulation workers.
-
-Change the ``libE_specs`` in **run_libe_forces.py** as follows.
-
-   .. code-block:: python
-
-    nsim_workers = ensemble.nworkers
-
-    # Persistent gen does not need resources
-    ensemble.libE_specs = LibeSpecs(
-        gen_on_manager=True,
-
-and run with::
-
-    python run_libe_forces.py -n 4
-
 To watch video
 ^^^^^^^^^^^^^^
 

diff --git a/docs/platforms/platforms_index.rst b/docs/platforms/platforms_index.rst
@@ -24,35 +24,21 @@ simulation worker, and libEnsemble will distribute user applications across the
 node allocation. This is the **most common approach** where each simulation
 runs an MPI application.
 
-The generator will run on a worker by default, but if running a single generator,
-the :ref:`libE_specs<datastruct-libe-specs>` option **gen_on_manager** is recommended,
-which runs the generator on the manager (using a thread) as below.
+.. image:: ../images/centralized_gen_on_manager.png
+        :alt: centralized
+        :scale: 55
 
-.. list-table::
-   :widths: 60 40
+A SLURM batch script may include:
 
-   * - .. image:: ../images/centralized_gen_on_manager.png
-          :alt: centralized
-          :scale: 55
+.. code-block:: bash
 
-     - In calling script:
+    #SBATCH --nodes 3
 
-       .. code-block:: python
-          :linenos:
+    python run_libe_forces.py --nworkers 3
 
-          ensemble.libE_specs = LibeSpecs(
-              gen_on_manager=True,
-          )
-
-       A SLURM batch script may include:
-
-       .. code-block:: bash
-
-          #SBATCH --nodes 3
-
-          python run_libe_forces.py --nworkers 3
-
-When using **gen_on_manager**, set ``nworkers`` to the number of workers desired for running simulations.
+If running multiple generator processes instead, then set the
+:ref:`libE_specs<datastruct-libe-specs>` option **gen_on_worker** so that multiple
+worker processes can run multiple generator instances.
 
 Dedicated Mode
 ^^^^^^^^^^^^^^
@@ -62,32 +48,29 @@ True, the MPI executor will not launch applications on nodes where libEnsemble P
 processes (manager and workers) are running. Workers launch applications onto the
 remaining nodes in the allocation.
 
-.. list-table::
-   :widths: 60 40
-
-   * - .. image:: ../images/centralized_dedicated.png
-          :alt: centralized dedicated mode
-          :scale: 30
 
-     - In calling script:
+.. image:: ../images/centralized_dedicated.png
+    :alt: centralized dedicated mode
+    :scale: 30
 
-       .. code-block:: python
-          :linenos:
+In calling script:
 
-          ensemble.libE_specs = LibeSpecs(
-              num_resource_sets=2,
-              dedicated_mode=True,
-          )
+.. code-block:: python
+    :linenos:
 
-       A SLURM batch script may include:
+    ensemble.libE_specs = LibeSpecs(
+        gen_on_worker=True,
+        num_resource_sets=2,
+        dedicated_mode=True,
+    )
 
-       .. code-block:: bash
+A SLURM batch script may include:
 
-          #SBATCH --nodes 3
+.. code-block:: bash
 
-          python run_libe_forces.py --nworkers 3
+    #SBATCH --nodes 3
 
-Note that **gen_on_manager** is not set in the above example.
+    python run_libe_forces.py --nworkers 3
 
 Distributed Running
 -------------------
@@ -137,8 +120,7 @@ Zero-resource workers
 ---------------------
 
 Users with persistent ``gen_f`` functions may notice that the persistent workers
-are still automatically assigned system resources. This can be resolved by using
-the ``gen_on_manager`` option or by
+are still automatically assigned system resources. This can be resolved by
 :ref:`fixing the number of resource sets<zero_resource_workers>`.
 
 Assigning GPUs

diff --git a/docs/running_libE.rst b/docs/running_libE.rst
@@ -12,13 +12,6 @@ determine the parameters/inputs for simulations. Simulator functions run and
 manage simulations, which often involve running a user application (see
 :doc:`Executor<executor/ex_index>`).
 
-.. note::
-    As of version 1.3.0, the generator can be run as a thread on the manager,
-    using the :ref:`libE_specs<datastruct-libe-specs>` option **gen_on_manager**.
-    When using this option, set the number of workers desired for running
-    simulations. See :ref:`Running generator on the manager<gen-on-manager>`
-    for more details.
-
 To use libEnsemble, you will need a calling script, which in turn will specify
 generator and simulator functions. Many :doc:`examples<examples/examples_index>`
 are available.
@@ -161,29 +154,6 @@ If this example was run as::
 
 No simulations will be able to run.
 
-.. _gen-on-manager:
-
-Running generator on the manager
---------------------------------
-
-The majority of libEnsemble use cases run a single generator. The
-:ref:`libE_specs<datastruct-libe-specs>` option **gen_on_manager** will cause
-the generator function to run on a thread on the manager. This can run
-persistent user functions, sharing data structures with the manager, and avoids
-additional communication to a generator running on a worker. When using this
-option, the number of workers specified should be the (maximum) number of
-concurrent simulations.
-
-If modifying a workflow to use ``gen_on_manager`` consider the following.
-
-* Set ``nworkers`` to the number of workers desired for running simulations.
-* If using :meth:`add_unique_random_streams()<tools.add_unique_random_streams>`
-  to seed random streams, the default generator seed will be zero.
-* If you have a line like ``libE_specs["nresource_sets"] = nworkers -1``, this
-  line should be removed.
-* If the generator does use resources, ``nresource_sets`` can be increased as needed
-  so that the generator and all simulations are resourced.
-
 Environment Variables
 ---------------------
 

diff --git a/docs/tutorials/executor_forces_tutorial.rst b/docs/tutorials/executor_forces_tutorial.rst
@@ -336,44 +336,6 @@ These may require additional browsing of the documentation to complete.
 
         ...
 
-Running the generator on the manager
-------------------------------------
-
-As of version 1.3.0, the generator can be run on a thread on the manager,
-using the :ref:`libE_specs<datastruct-libe-specs>` option **gen_on_manager**.
-
-Change the libE_specs as follows.
-
-   .. code-block:: python
-    :linenos:
-    :lineno-start: 28
-
-    nsim_workers = ensemble.nworkers
-
-    # Persistent gen does not need resources
-    ensemble.libE_specs = LibeSpecs(
-        gen_on_manager=True,
-        sim_dirs_make=True,
-        ensemble_dir_path="./test_executor_forces_tutorial",
-    )
-
-When running set ``nworkers`` to the number of workers desired for running simulations.
-E.g., Instead of:
-
-.. code-block:: bash
-
-    python run_libe_forces.py --nworkers 5
-
-use:
-
-.. code-block:: bash
-
-    python run_libe_forces.py --nworkers 4
-
-Note that as the generator random number seed will be zero instead of one, the checksum will change.
-
-For more information see :ref:`Running generator on the manager<gen-on-manager>`.
-
 Running forces application with input file
 ------------------------------------------