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 0x7f722c29a570>
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:0] rank = 0, size = 2
[stdout:1] rank = 1, 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] 2026-08-03 06:27:10.030 ( 1.031s) [ 7F454E032140]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY=
[stderr:1] 2026-08-03 06:27:10.030 ( 1.031s) [ 7FDD2D1A6140]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY=
[output:1]
[output:0]
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': 2542, 'identifier': 'ipcontroller-1785738421-6v5w-2523'}
Stopping engine(s): 1785738423
Output for ipengine-1785738421-6v5w-1785738423-2523: 2026-08-03 06:27:03.476 [IPEngine] Loading connection info from $IPP_CONNECTION_INFO 2026-08-03 06:27:03.476 [IPEngine] Loading connection info from $IPP_CONNECTION_INFO 2026-08-03 06:27:03.476 [IPEngine] WARNING | Not using CurveZMQ security 2026-08-03 06:27:03.476 [IPEngine] WARNING | Not using CurveZMQ security 2026-08-03 06:27:03.500 [IPEngine.0] Registering with controller at tcp://127.0.0.1:34379 2026-08-03 06:27:03.500 [IPEngine.1] Registering with controller at tcp://127.0.0.1:34379 2026-08-03 06:27:03.501 [IPEngine.0] Requesting id: 0 2026-08-03 06:27:03.501 [IPEngine.1] Requesting id: 1 2026-08-03 06:27:03.503 [IPEngine.0.0] Shell_addrs: ['tcp://127.0.0.1:42305', 'tcp://127.0.0.1:40135', 'tcp://127.0.0.1:53583'] 2026-08-03 06:27:03.503 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:42305 2026-08-03 06:27:03.503 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:40135 2026-08-03 06:27:03.503 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:53583 2026-08-03 06:27:03.503 [IPEngine.0.0] Starting nanny 2026-08-03 06:27:03.504 [IPEngine.1.1] Shell_addrs: ['tcp://127.0.0.1:42305', 'tcp://127.0.0.1:40135', 'tcp://127.0.0.1:47293'] 2026-08-03 06:27:03.504 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:42305 2026-08-03 06:27:03.504 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:40135 2026-08-03 06:27:03.504 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:47293 2026-08-03 06:27:03.504 [IPEngine.1.1] Starting nanny 2026-08-03 06:27:03.918 [KernelNanny.0] Starting kernel nanny for engine 0, pid=2575, nanny pid=2587 2026-08-03 06:27:03.918 [KernelNanny.1] Starting kernel nanny for engine 1, pid=2576, nanny pid=2588 2026-08-03 06:27:03.918 [KernelNanny.0] Nanny watching parent pid 2575. 2026-08-03 06:27:03.918 [KernelNanny.1] Nanny watching parent pid 2576. 2026-08-03 06:27:03.994 [IPEngine.0.0] Loading IPython extension: storemagic 2026-08-03 06:27:03.995 [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() 2026-08-03 06:27:03.995 [IPEngine.1.1] Loading IPython extension: storemagic 2026-08-03 06:27:03.996 [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() 2026-08-03 06:27:03.997 [IPEngine.0.0] WARNING | debugpy_stream undefined, debugging will not be enabled 2026-08-03 06:27:03.998 [IPEngine.1.1] WARNING | debugpy_stream undefined, debugging will not be enabled 2026-08-03 06:27:04.004 [IPEngine.0.0] Starting to monitor the heartbeat signal from the hub every 3500 ms. 2026-08-03 06:27:04.004 [IPEngine.0.0] Completed registration with id 0 2026-08-03 06:27:04.008 [IPEngine.1.1] Starting to monitor the heartbeat signal from the hub every 3500 ms. 2026-08-03 06:27:04.009 [IPEngine.1.1] Completed registration with id 1 2026-08-03 06:27:08.769 [IPEngine.0.0] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_1 2026-08-03 06:27:08.770 [IPEngine.1.1] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_2 2026-08-03 06:27:08.981 [IPEngine.0.0] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_3 2026-08-03 06:27:08.982 [IPEngine.1.1] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_4 2026-08-03 06:27:09.994 [IPEngine.0.0] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_5 2026-08-03 06:27:09.995 [IPEngine.1.1] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_6 2026-08-03 06:27:10.007 [IPEngine.0.0] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_7 2026-08-03 06:27:10.008 [IPEngine.1.1] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_8 2026-08-03 06:27:10.024 [IPEngine.0.0] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_9 2026-08-03 06:27:10.024 [IPEngine.1.1] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_10 2026-08-03 06:27:10.030 ( 1.031s) [ 7FDD2D1A6140]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY= 2026-08-03 06:27:10.030 ( 1.031s) [ 7F454E032140]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY= 2026-08-03 06:27:10.371 [IPEngine.0.0] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_11 2026-08-03 06:27:10.372 [IPEngine.1.1] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_12 2026-08-03 06:27:10.384 [IPEngine.0.0] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_13 2026-08-03 06:27:10.385 [IPEngine.1.1] Handling execute_request: 86a18336-10be808951810fd7977430e5_2523_14 2026-08-03 06:27:11.176 [KernelNanny.1] Pipe closed, parent 2576 has status: zombie 2026-08-03 06:27:11.176 [KernelNanny.0] Pipe closed, parent 2575 has status: zombie 2026-08-03 06:27:11.176 [KernelNanny.0] Notifying Hub that our parent has shut down 2026-08-03 06:27:11.176 [KernelNanny.1] Notifying Hub that our parent has shut down
engine set stopped 1785738423: {'exit_code': 1, 'pid': 2570, 'identifier': 'ipengine-1785738421-6v5w-1785738423-2523'}