Tempfiles when using shiny - r

Question

I'm developing a shiny application where the user can upload a file and select X parameters, after that he press a button and it generates 5 plots (ggplot2 and barplot) and also a dynamic data table (DT). Also, I want to put my shiny app into a linux server.
I'm using tempfiles() for each file I'm using to create the plots and also the DT.
After that, my question is:
When the user closes the shiny app (close the window), do the tempfiles autodelete?
If not, what can I do to delete the tempfiles?
My tries:
session$onSessionEnded(function() {
if (!is.null(x1)) {
file.remove(x1)
}
if (!is.null(x2)) {
file.remove(x2)
}
if (!is.null(x3)) {
file.remove(x3)
}
if (!is.null(x4)) {
file.remove(x4)
}
if (!is.null(xx)) {
file.remove(xx)
}
})
Or:
session$onSessionEnded(function() {
files <- list.files(tempdir(), full.names = T, pattern = "^file")
file.remove(files)
})
With that code I delete the tempfiles when user presses the button once, and if the user presses the button more than 1 time then the window closes, and it will only delete the last generated files. The second part deletes all files at the temp dir but that affects to the other users?(I think yes so that's why I need another solution).
The .png tempfiles generated by ggplot and barplot doesn't autodelete.
My worry is that if the tempfiles won't autodelete and the linux server will collapse because of a lot of tempfiles.
Hope you can solve my doubts. Att Joan.

Answer 1

You can use the deleteFile=TRUE parameter if you want a render function to automatically delete your temporary files:
shinyServer(function(input, output, clientData) {
output$myImage <- renderImage({
# A temp file to save the output.
# This file will be removed later by renderImage
outfile <- tempfile(fileext='.png')
# Generate the PNG
png(outfile, width=400, height=300)
hist(rnorm(input$obs), main="Generated in renderImage()")
dev.off()
# Return a list containing the filename
list(src = outfile,
contentType = 'image/png',
width = 400,
height = 300,
alt = "This is alternate text")
}, deleteFile = TRUE)
})
A temp file is created to save the output, and that file is later automatically removed because of the deleteFile=TRUE argument.
The default Shiny (shiny.R) also has a built-in mechanism that clear file upload directories if that's your concern. The following code remove the upload directory when the session ends:
registerSessionEndCallbacks = function() {
# This is to be called from the initialization. It registers functions
# that are called when a session ends.
# Clear file upload directories, if present
self$onSessionEnded(private$fileUploadContext$rmUploadDirs)
}
Another point regarding manually deleting your temp files (as what you were attempting): the plot will have to render every time the user switched to another tab or resize his / her browser window, so if you're manually deleting the file, it may be inefficient since it needs to be re-rendered again. The onSessionEnded solution is nicer as it confirms that the session has ended.
session$onSessionEnded(function() {
if (!is.null(input$file1)) {
file.remove(input$file1$datapath)
}
})