Application System

Description

The Application block within an input file is utilized to explicitly specify the application type used for the input file. The application type should be provided using the "type" parameter in the Application block. This block is parsed before the MOOSE application is actually built. If any mismatch between the registered application type and the user-selected type is detected, the system will immediately throw an error and stop the setup of the simulation.

Reducing the number of threads for an application

The user may pass "num_threads" in addition to the command line argument --n-threads to reduce the number of threads for an application. The --n-threads value then indicates the maximum number of threads that can be used, while each application, for example in the context of MultiApps, may only use "num_threads" threads.

note

--n-threads sets the number of threads used by several of libMesh's threaded routines. These routines will create a thread pool at this maximum size. If you are also running other threaded applications at the same time and the combined thread count exceeds the system's capacity, this can cause slowdowns.

Example

The following input file snippet demonstrates the use of the Application block.

[Application<<<{"href": "index.html"}>>>]
  type = MooseTestApp
[]

Available Actions

Moose App
CreateApplicationBlockActionAdds application and application related parameters.

(test/tests/multiapps/application_block_multiapps/application_block_sub.i)

[Application]
  type = MooseTestApp
[]

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 10
  ny = 10
[]

[Variables]
  [u]
  []
[]

[Kernels]
  [diff]
    type = Diffusion
    variable = u
  []
  [td]
    type = TimeDerivative
    variable = u
  []
[]

[BCs]
  [left]
    type = DirichletBC
    variable = u
    boundary = left
    value = 0
  []
  [right]
    type = DirichletBC
    variable = u
    boundary = right
    value = 1
  []
[]

[Executioner]
  type = Transient
  num_steps = 1
  dt = 1

  solve_type = 'PJFNK'

  petsc_options_iname = '-pc_type -pc_hypre_type'
  petsc_options_value = 'hypre boomeramg'
[]

[Outputs]
  exodus = true
[]

Description
Reducing the number of threads for an application
Example
Available Actions