delay session initialization.

app.R

@@ -7,7 +7,6 @@ source("model-session.R")
 #repo <- "stabilityai/stablelm-tuned-alpha-3b"
 repo <- "EleutherAI/pythia-70m"
 sess <- model_session$new()
-model_loaded <- sess$load_model(repo)
 
 max_n_tokens <- 100
 system_prompt = "<|SYSTEM|># StableLM Tuned (Alpha version)
@@ -35,6 +34,7 @@ ui <- page_fillable(
 )
 
 server <- function(input, output, session) {
+  model_loaded <- sess$load_model(repo)
   
   prompt <- reactiveVal(value = system_prompt)
   n_tokens <- reactiveVal(value = 0)

model-session.R

@@ -6,12 +6,17 @@ model_session <- R6::R6Class(
   lock_objects = FALSE,
   public = list(
     initialize = function() {
-      self$sess <- promise_session$new()
+      self$sess <- NULL
       self$temperature <- 1
       self$top_k <- 50
       self$is_loaded <- FALSE
     },
     load_model = function(repo) {
+      if (!is.null(self$sess)) {
+        cat("Model is already loaded.", "\n")
+        return(self$sess$call(function() "done"))
+      }
+      self$sess <- promise_session$new()
       self$sess$call(args = list(repo = repo), function(repo) {
         library(torch)
         library(zeallot)