shiny.benchmark

Tools to measure performance improvements in shiny apps.

shiny.benchmark is a tool aimed to measure and compare the performance of different versions of a shiny application. Based on a list of different application versions, accessible by a git repo by its refs (commit hash or branch name), the user can write instructions to be executed using Cypress or shinytest2. These instructions are then evaluated by the different versions of your shiny application and therefore the performance's improvement/deterioration (time elapsed) are be recorded.

The package is flexible enough to allow different sets of tests for the different refs as well as different package versions (via renv). Also, the user can replicate the tests to have more accurate measures of performance.

How to install?

remotes::install_github("Appsilon/shiny.benchmark")

Dependencies

shiny.benchmark can use two different engines to test the change in the performance of your application: shinytest2 and Cypress. The latter requires Node (version 12 or higher) and yarn (version 1.22.17 or higher) to be available. To install them on your computer, follow the guidelines on the documentation pages:

• Node
• yarn

Besides that, on Linux, it might be required to install other Cypress dependencies. Check the documentation to find out more.

How to use it?

The best way to start using shiny.benchmark is through an example. If you want a start point, you can use the load_example function. In order to use this, create a new folder in your computer and use the following code to generate an application to serve us as example for our performance checks:

library(shiny.benchmark)

load_example(path = "path/to/new/project")

It will create some useful files under path/to/new/project. The most important one is the run_tests.R which provides several instructions at the very top.

As we are comparing versions of the same application, we need different app versions in different branches/commits in git. Start using cd app; git init to initiate git inside app/ folder.

Get familiar with app/server.R file in order to generate more interesting scenarios. The basic idea is to use the Sys.sleep function to simulate some app's functionalities. Remember that, when running the benchmark, that is the amount of time it will take to measure the performance.

When you are ready, commit your changes in master/main using git add .; git commit -m "your commit message". Make some editions and commit these new changes into a new branch or in the same branch your are testing (it will have a different commit hash). Repeat the process adding as many new modifications as you want. E.g. add renv, add more tests, change the names of the tests/test files and so on.

Here is a complete example on how to setup your git:

# starting
git init
echo .Rproj.user >> .gitignore
echo *.Rproj >> .gitignore
echo .Rprofile >> .gitignore
echo renv >> .gitignore
echo .Rprofile >> .gitignore

# master
git add .
git commit -m "first commit"

# develop (decrease Sys.sleep times in server.R)
git checkout -b develop
git add .
git commit -m "improving performance"

## Using renv
git branch renv_shiny1 develop
git checkout renv_shiny1
R -e 'renv::init()'
git add .
git commit -m "renv active"

## Downgrading shiny
git checkout -b renv_shiny2
R -e 'renv::install("shiny@1.7.0")'
R -e 'renv::snapshot()'
git add .
git commit -m "downgrading shiny"

## Switching back to develop
git checkout develop

Now you are ready to go. The benchmark function provides several arguments to make your life easier when running your performance checks. The mandatory arguments are:

• commit_list: A vector with commits, branches or anything else you can use in git checkout
• cypress_dir or shinytest2_dir: Folder containing the tests we want to check the performance. In our case it is tests/cypress and tests respectively.

The default behavior is to try to use renv in your project. If you do not have the renv structure, you can turn renv off using use_renv = FALSE

library(shiny.benchmark)

# commits to compare
commit_list <- c("develop", "renv_shiny1", "renv_shiny2")

# run performance check using Cypress
benchmark(
  commit_list = commit_list,
  cypress_dir = "tests/cypress"
)

That is all you need to run your Cypress tests. If you don't use Cypress, you may want to use shinytest2 instead:

benchmark(
  commit_list = commit_list,
  shinytest2_dir = "tests"
)

To run just specific tests, you can take advantage of the tests_pattern argument. It will filter the test file's names based on regular expression:

benchmark(
  commit_list = commit_list,
  shinytest2_dir = "tests",
  tests_pattern = "use_this_one_[0-9]"
)

If your project has renv structure, you can set use_renv to TRUE to guarantee that, for each application version your are using the correct packages. If you want to approve/reprove renv::restore(), you can set renv_prompt = TRUE.

benchmark(
  commit_list = commit_list,
  shinytest2_dir = "tests",
  tests_pattern = "use_this_one_[0-9]",
  use_renv = TRUE, # default
  renv_prompt = TRUE
)

To have more accurate information about the time your application takes to perform some actions, you may need to replicate the tests. In this case, you can use the n_rep argument:

out <- benchmark(
  commit_list = commit_list,
  cypress_dir = "tests/cypress",
  tests_pattern = "use_this_one_[0-9]",
  use_renv = FALSE,
  n_rep = 15
)

out

For fast information about the tests results, you can use the summary and also the plot methods:

summary(out)
plot(out)

How to contribute?

If you want to contribute to this project please submit a regular PR, once you're done with new feature or bug fix.

Reporting a bug is also helpful - please use GitHub issues and describe your problem as detailed as possible.

Appsilon

Appsilon is a Posit (formerly RStudio) Full Service Certified Partner. Learn more at appsilon.com.

Get in touch opensource@appsilon.com