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 0x7f1f9c9d37a0>
The jupyter magic %%px will run the following cells on the ipyparallel cluster.
%%px
import firedrake # 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 = firedrake.UnitSquareMesh(
6, 6, comm=comm_world, distribution_parameters={"partitioner_type": "simple"})
Plot the mesh defined on MPI_COMM_WORLD. Each rank will plot its local cells, and their neighbors (called halos in firedrake).
%%px
viskex.firedrake.plot_mesh(square_world)
[stderr:1] 2026-08-03 07:27:11.883 ( 1.027s) [ 7FC9B6718080]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY=
[stderr:0] 2026-08-03 07:27:11.882 ( 1.026s) [ 7FF4DFFB0080]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 = firedrake.UnitSquareMesh(
6, 6, comm=comm_self, distribution_parameters={"partitioner_type": "simple"})
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.firedrake.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': 2475, 'identifier': 'ipcontroller-1785738422-yku7-2456'}
Stopping engine(s): 1785738424
Output for ipengine-1785738422-yku7-1785738424-2456: 2026-08-03 07:27:04.534 [IPEngine] Loading connection info from $IPP_CONNECTION_INFO 2026-08-03 07:27:04.534 [IPEngine] WARNING | Not using CurveZMQ security 2026-08-03 07:27:04.546 [IPEngine] Loading connection info from $IPP_CONNECTION_INFO 2026-08-03 07:27:04.546 [IPEngine] WARNING | Not using CurveZMQ security 2026-08-03 07:27:04.779 [IPEngine.0] Registering with controller at tcp://127.0.0.1:41103 2026-08-03 07:27:04.779 [IPEngine.1] Registering with controller at tcp://127.0.0.1:41103 2026-08-03 07:27:04.779 [IPEngine.0] Requesting id: 0 2026-08-03 07:27:04.779 [IPEngine.1] Requesting id: 1 2026-08-03 07:27:04.781 [IPEngine.0.0] Shell_addrs: ['tcp://127.0.0.1:39317', 'tcp://127.0.0.1:34567', 'tcp://127.0.0.1:55315'] 2026-08-03 07:27:04.782 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:39317 2026-08-03 07:27:04.782 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:34567 2026-08-03 07:27:04.782 [IPEngine.0.0] Connecting shell to tcp://127.0.0.1:55315 2026-08-03 07:27:04.782 [IPEngine.0.0] Starting nanny 2026-08-03 07:27:04.783 [IPEngine.1.1] Shell_addrs: ['tcp://127.0.0.1:39317', 'tcp://127.0.0.1:34567', 'tcp://127.0.0.1:46703'] 2026-08-03 07:27:04.783 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:39317 2026-08-03 07:27:04.783 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:34567 2026-08-03 07:27:04.783 [IPEngine.1.1] Connecting shell to tcp://127.0.0.1:46703 2026-08-03 07:27:04.783 [IPEngine.1.1] Starting nanny 2026-08-03 07:27:05.229 [KernelNanny.1] Starting kernel nanny for engine 1, pid=2511, nanny pid=2522 2026-08-03 07:27:05.229 [KernelNanny.0] Starting kernel nanny for engine 0, pid=2510, nanny pid=2521 2026-08-03 07:27:05.229 [KernelNanny.1] Nanny watching parent pid 2511. 2026-08-03 07:27:05.229 [KernelNanny.0] Nanny watching parent pid 2510. 2026-08-03 07:27:05.299 [IPEngine.0.0] Loading IPython extension: storemagic 2026-08-03 07:27:05.299 [IPEngine.1.1] Loading IPython extension: storemagic 2026-08-03 07:27:05.300 [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 07:27:05.300 [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 07:27:05.301 [IPEngine.0.0] WARNING | debugpy_stream undefined, debugging will not be enabled 2026-08-03 07:27:05.302 [IPEngine.1.1] WARNING | debugpy_stream undefined, debugging will not be enabled 2026-08-03 07:27:05.303 [IPEngine.1.1] Starting to monitor the heartbeat signal from the hub every 3500 ms. 2026-08-03 07:27:05.303 [IPEngine.0.0] Starting to monitor the heartbeat signal from the hub every 3500 ms. 2026-08-03 07:27:05.303 [IPEngine.0.0] Completed registration with id 0 2026-08-03 07:27:05.304 [IPEngine.1.1] Completed registration with id 1 2026-08-03 07:27:09.799 [IPEngine.0.0] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_1 2026-08-03 07:27:09.800 [IPEngine.1.1] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_2 2026-08-03 07:27:11.249 [IPEngine.0.0] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_3 2026-08-03 07:27:11.249 [IPEngine.1.1] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_4 2026-08-03 07:27:11.804 [IPEngine.0.0] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_5 2026-08-03 07:27:11.805 [IPEngine.1.1] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_6 2026-08-03 07:27:11.816 [IPEngine.0.0] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_7 2026-08-03 07:27:11.816 [IPEngine.1.1] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_8 2026-08-03 07:27:11.876 [IPEngine.0.0] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_9 2026-08-03 07:27:11.877 [IPEngine.1.1] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_10 2026-08-03 07:27:11.882 ( 1.026s) [ 7FF4DFFB0080]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY= 2026-08-03 07:27:11.883 ( 1.027s) [ 7FC9B6718080]vtkXOpenGLRenderWindow.:1460 WARN| bad X server connection. DISPLAY= 2026-08-03 07:27:12.725 [IPEngine.0.0] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_11 2026-08-03 07:27:12.725 [IPEngine.1.1] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_12 2026-08-03 07:27:12.741 [IPEngine.1.1] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_14 2026-08-03 07:27:12.741 [IPEngine.0.0] Handling execute_request: 03d7c2d5-7fe033dc674b3f7ebfe9d662_2456_13
engine set stopped 1785738424: {'exit_code': 1, 'pid': 2503, 'identifier': 'ipengine-1785738422-yku7-1785738424-2456'}