Shiny app shows a blank page when re-opened with rstudioapi::viewer()

[atusy]

System details

Browser Version: Firefox 124.0.1 _{(Google Chrome 122.0.6261.94 is OK)}

Output of sessionInfo():

> sessionInfo()
R version 4.3.2 (2023-10-31)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 22.04.3 LTS

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3 
LAPACK: /usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblasp-r0.3.20.so;  LAPACK version 3.10.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8       
 [4] LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                  LC_ADDRESS=C              
[10] LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

time zone: Etc/UTC
tzcode source: system (glibc)

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
 [1] digest_0.6.33     later_1.3.2       R6_2.5.1          httpuv_1.6.13    
 [5] fastmap_1.1.1     xfun_0.41         magrittr_2.0.3    shiny_1.8.1.9000 
 [9] htmltools_0.5.7   lifecycle_1.0.4   servr_0.28        ps_1.7.5         
[13] promises_1.2.1    cli_3.6.2         processx_3.8.3    xtable_1.8-4     
[17] callr_3.7.3       compiler_4.3.2    rstudioapi_0.15.0 tools_4.3.2      
[21] mime_0.12         Rcpp_1.0.11       jsonlite_1.8.8    rlang_1.1.2 

Example application or steps to reproduce the problem

# Create Shiny App in the background
callr::r_bg(function() {
  shiny::runGadget(
    shiny::basicPage("Hello"),
    function(input, output) {},
    port = 1000
  )
})

# Open Shiny App in RStudio's viewer
# On repeat calling viewer, `2n`-th tries become blank page. `2n-1`-th tries are okay.
rstudioapi::viewer("http://127.0.0.1:1000")

Describe the problem in detail

As I have shown in the above example, viewing shiny app for the 2n-th times show blank pages...
This happens on RStudio Server on Firefox, but not on Chrome.

A similar example with servr package in the below does not show such a behavior.
So I guess there is something wrong with Shiny, but not sure...

callr::r_bg(function() {
  s = servr::create_server(port = 1001, handler = function(req) {
    list(status = 200L, body = paste("Success:", req$PATH_INFO))
  })
  while(TRUE) {
    NULL
  }
})

rstudioapi::viewer("http://127.0.0.1:1001")

[gadenbuie]

Hi @atusy, thanks for the bug report! Two follow up questions:

1. Which version of RStudio Server are you using and how are you running it?
2. Does this issue happen with previous released versions of shiny, e.g. v1.8.0 or v1.7.5?

[atusy]

@gadenbuie

Thank you for the quick response. Here you go.

1. RStudio Server: 2023.12.0 Build 369, docker
2. Happens on various Shiny versions: dev, v1.8.1, v1.8.0, v1.7.5