In CmdStanR, can you find the path to the tmpdir?

Interfaces
1

because programs are segfaulting, can’t get debug info out for CmdStanR fit objects because there is no fit object.

users are trying to debug an indexing error in CmdStanR by putting print statements into their Stan program, but no output to console. default for show_messages is TRUE, but nothing to console - expecting print stmts, which, underlyingly are being sent to stdout.

2

Probably doesn’t help, but I always do ll - rt /tmp and/or just grep all files in /tmp/*/. Works fine on Ubuntu.

3

Not sure I follow, are you saying a user added prints and those were not displayed?

If I just run

library(cmdstanr)

file <- file.path(cmdstan_path(), "examples", "bernoulli", "bernoulli.stan")
data_file <- file.path(cmdstan_path(), "examples", "bernoulli", "bernoulli.data.json")
mod <- cmdstan_model(file)
fit <- mod$sample(data = data_file)

where I changed the model to

model {
  theta ~ beta(1,1);  // uniform prior on interval 0,1
  y ~ bernoulli(theta);
  print(theta);
}

I see all the prints.

...
Chain 4 0.218246 
Chain 4 0.2636 
Chain 4 0.210149 
Chain 4 0.245909 
Chain 4 0.245909 
Chain 4 0.213425 
Chain 4 0.22143 
Chain 4 0.263097 
Chain 4 0.22143 
Chain 4 0.188243 
Chain 4 0.294658 
Chain 4 0.316411 
Chain 4 0.188243 
Chain 4 0.148463 
Chain 4 0.148463 
Chain 4 0.0712568 
Chain 4 0.429266 
Chain 4 0.511316 
Chain 4 0.0712568 
Chain 4 0.0487743 
Chain 4 0.0712568 
Chain 4 0.0641963 
Chain 4 0.0641963 
Chain 4 0.0847295 
Chain 4 0.0847295 
....

In R tempdir() will print the current temp folder (for the R sessions) which is also where cmdstanr will do its work. But I am not sure if that will help?

4

yes, this is secondhand - Bob was on a call helping a user debug their program, using CmdStanR. the program segfaulted and the print stmts never made it to the terminal.

I think the tempdir cmd would have helped - not sure.

(note - this is an issue for CmdStanPy - Options for streaming CmdStan's stdout, stderr to Python console · Issue #152 · stan-dev/cmdstanpy · GitHub -
which should be discussed in its own thread, or just fixed.)