While these tutorials are typically meant to be visualized in serial, viskex also runs in parallel. To exemplify this, we will show a parallel case using ipyparallel.
First of all, we start a ipyparallel MPI cluster with 2 processes.
import ipyparallel as ipp
cluster = ipp.Cluster(engines="MPI", profile="mpi", n=2)
cluster.start_and_connect_sync()
Starting 2 engines with <class 'ipyparallel.cluster.launcher.MPIEngineSetLauncher'>
<ipyparallel.client.client.Client at 0x7f47945b41d0>
The jupyter magic %%px will run the following cells on the ipyparallel cluster.
%%px
import dolfinx.mesh # noqa: E402
import mpi4py.MPI # noqa: E402
%%px
import viskex # noqa: E402
To confirm that we are running in parallel, we can print the rank of the current process and the total number of processes.
%%px
comm_world = mpi4py.MPI.COMM_WORLD
print(f"rank = {comm_world.rank}, size = {comm_world.size}")
[stdout:1] rank = 1, size = 2
[stdout:0] rank = 0, size = 2
Generate a mesh on MPI_COMM_WORLD of the unit square by dividing each edge of the square in 6 segments.
%%px
square_world = dolfinx.mesh.create_unit_square(comm_world, 6, 6)
Plot the mesh defined on MPI_COMM_WORLD. Each rank will plot its local cells, and their neighbors (called ghosts in dolfinx).
%%px
viskex.dolfinx.plot_mesh(square_world)
[stderr:0] 2026-05-25 07:19:33.655 ( 1.033s) [ 7FB5B7442140]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY=
[stderr:1] 2026-05-25 07:19:33.655 ( 1.033s) [ 7F1900863140]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY=
[output:0]
[output:1]
For comparison, we can generate a similar mesh on MPI_COMM_SELF. Each rank will have its own copy of the whole mesh.
%%px
comm_self = mpi4py.MPI.COMM_SELF
square_self = dolfinx.mesh.create_unit_square(comm_self, 6, 6)
Plot the mesh defined on MPI_COMM_SELF. Each rank will produce a plot which is visually the same, since each rank has its own copy of the same mesh.
%%px
viskex.dolfinx.plot_mesh(square_self)
[output:1]
[output:0]
We finally stop the ipyparallel cluster. Note that when running with Run -> Run all cells all interactive plots will be closed when the kernel executes this cell.
cluster.stop_cluster_sync()
Stopping controller
Controller stopped: {'exit_code': 0, 'pid': 2754, 'identifier': 'ipcontroller-1779693565-jb1g-2735'}
Stopping engine(s): 1779693566
Output for ipengine-1779693565-jb1g-1779693566-2735: 2026-05-25 07:19:26.942 [IPEngine] Loading connection info from $IPP_CONNECTION_INFO 2026-05-25 07:19:26.942 [IPEngine] WARNING | Not using CurveZMQ security 2026-05-25 07:19:26.958 [IPEngine] Loading connection info from $IPP_CONNECTION_INFO 2026-05-25 07:19:26.959 [IPEngine] WARNING | Not using CurveZMQ security 2026-05-25 07:19:26.971 [IPEngine.0] Registering with controller at tcp://127.0.0.1:36149 2026-05-25 07:19:26.971 [IPEngine.1] Registering with controller at tcp://127.0.0.1:36149 2026-05-25 07:19:26.971 [IPEngine.0] Requesting id: 0 2026-05-25 07:19:26.972 [IPEngine.1] Requesting id: 1 2026-05-25 07:19:26.974 [IPEngine.0.0] Shell_addrs: ['tcp://127.0.0.1:46131', 'tcp://127.0.0.1:43379', 'tcp://127.0.0.1:57211'] 2026-05-25 07:19:26.974 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:46131 2026-05-25 07:19:26.974 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:43379 2026-05-25 07:19:26.974 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:57211 2026-05-25 07:19:26.974 [IPEngine.0.0] Starting nanny 2026-05-25 07:19:26.975 [IPEngine.1.1] Shell_addrs: ['tcp://127.0.0.1:46131', 'tcp://127.0.0.1:43379', 'tcp://127.0.0.1:49825'] 2026-05-25 07:19:26.975 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:46131 2026-05-25 07:19:26.975 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:43379 2026-05-25 07:19:26.976 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:49825 2026-05-25 07:19:26.976 [IPEngine.1.1] Starting nanny 2026-05-25 07:19:27.391 [KernelNanny.0] Starting kernel nanny for engine 0, pid=2787, nanny pid=2799 2026-05-25 07:19:27.392 [KernelNanny.0] Nanny watching parent pid 2787. 2026-05-25 07:19:27.394 [KernelNanny.1] Starting kernel nanny for engine 1, pid=2788, nanny pid=2800 2026-05-25 07:19:27.395 [KernelNanny.1] Nanny watching parent pid 2788. 2026-05-25 07:19:27.464 [IPEngine.0.0] Loading IPython extension: storemagic 2026-05-25 07:19:27.464 [IPEngine.0.0] Running code in user namespace: from mpi4py import MPI mpi_rank = MPI.COMM_WORLD.Get_rank() mpi_size = MPI.COMM_WORLD.Get_size() 2026-05-25 07:19:27.465 [IPEngine.1.1] Loading IPython extension: storemagic 2026-05-25 07:19:27.465 [IPEngine.1.1] Running code in user namespace: from mpi4py import MPI mpi_rank = MPI.COMM_WORLD.Get_rank() mpi_size = MPI.COMM_WORLD.Get_size() 2026-05-25 07:19:27.466 [IPEngine.0.0] WARNING | debugpy_stream undefined, debugging will not be enabled 2026-05-25 07:19:27.467 [IPEngine.1.1] WARNING | debugpy_stream undefined, debugging will not be enabled 2026-05-25 07:19:27.472 [IPEngine.0.0] Starting to monitor the heartbeat signal from the hub every 3500 ms. 2026-05-25 07:19:27.472 [IPEngine.0.0] Completed registration with id 0 2026-05-25 07:19:27.472 [IPEngine.1.1] Starting to monitor the heartbeat signal from the hub every 3500 ms. 2026-05-25 07:19:27.472 [IPEngine.1.1] Completed registration with id 1 2026-05-25 07:19:32.239 [IPEngine.0.0] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_1 2026-05-25 07:19:32.240 [IPEngine.1.1] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_2 2026-05-25 07:19:32.603 [IPEngine.0.0] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_3 2026-05-25 07:19:32.603 [IPEngine.1.1] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_4 2026-05-25 07:19:33.623 [IPEngine.0.0] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_5 2026-05-25 07:19:33.624 [IPEngine.1.1] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_6 2026-05-25 07:19:33.634 [IPEngine.1.1] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_8 2026-05-25 07:19:33.634 [IPEngine.0.0] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_7 2026-05-25 07:19:33.649 [IPEngine.0.0] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_9 2026-05-25 07:19:33.649 [IPEngine.1.1] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_10 2026-05-25 07:19:33.655 ( 1.033s) [ 7FB5B7442140]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY= 2026-05-25 07:19:33.655 ( 1.033s) [ 7F1900863140]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY= 2026-05-25 07:19:33.994 [IPEngine.0.0] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_11 2026-05-25 07:19:33.994 [IPEngine.1.1] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_12 2026-05-25 07:19:34.006 [IPEngine.0.0] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_13 2026-05-25 07:19:34.006 [IPEngine.1.1] Handling execute_request: 5fc66182-5caf5ae2775889f014399293_2735_14 2026-05-25 07:19:34.834 [KernelNanny.1] Pipe closed, parent 2788 has status: zombie 2026-05-25 07:19:34.834 [KernelNanny.1] Parent 2788 exited with status None. 2026-05-25 07:19:34.834 [KernelNanny.1] Notifying Hub that our parent has shut down 2026-05-25 07:19:34.849 [KernelNanny.0] Pipe closed, parent 2787 has status: zombie 2026-05-25 07:19:34.849 [KernelNanny.0] Notifying Hub that our parent has shut down
engine set stopped 1779693566: {'exit_code': 1, 'pid': 2782, 'identifier': 'ipengine-1779693565-jb1g-1779693566-2735'}