Capture more error info when workers fail to start up (#265)

Author: MichaelHatherly

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fix missing display maths output in Typst. Works around inconsistency in handling of markdown math syntax between Quarto output formats [#262]
+- Print out better errors when worker `julia` processes fail to start [#265]
 
 ## [v0.13.1] - 2025-02-18
 
@@ -383,3 +384,4 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [#255]: https://github.com/PumasAI/QuartoNotebookRunner.jl/issues/255
 [#257]: https://github.com/PumasAI/QuartoNotebookRunner.jl/issues/257
 [#262]: https://github.com/PumasAI/QuartoNotebookRunner.jl/issues/262
+[#265]: https://github.com/PumasAI/QuartoNotebookRunner.jl/issues/265

Project.toml

@@ -8,6 +8,7 @@ BSON = "fbb218c0-5317-5bc6-957e-2ee96dd4b1f0"
 Base64 = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"
 CommonMark = "a80b9123-70ca-4bc0-993e-6e3bcb318db6"
 Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"
+IOCapture = "b5f81e59-6552-4d32-b1f0-c071b021bf89"
 InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
 IterTools = "c8e1da08-722c-5040-9ed9-7db0dc04731e"
 JSON3 = "0f8b85d8-7281-11e9-16c2-39a750bddbf1"
@@ -29,6 +30,7 @@ BSON = "0.3"
 Base64 = "1.6"
 CommonMark = "0.8"
 Compat = "4"
+IOCapture = "0.2"
 InteractiveUtils = "1.6"
 IterTools = "1"
 JSON3 = "1"

src/Malt.jl

@@ -8,6 +8,7 @@ module Malt
 import ..QuartoNotebookRunner: UserError
 
 import BSON
+import IOCapture
 import Pkg
 import TOML
 using Sockets: Sockets
@@ -129,6 +130,17 @@ mutable struct Worker <: AbstractWorker
 
                 err_output = read(errors_log_file, String)
                 if isnothing(manifest_error)
+                    empty_result = IOCapture.capture(; rethrow = InterruptException) do
+                        run(_get_worker_cmd(; exe, env, exeflags, file = String(empty_file)))
+                    end
+                    if empty_result.error
+                        message = """
+                        Failed to start worker process.
+
+                        $(empty_result.output)
+                        """
+                        error(message)
+                    end
                     # Generic error reporting when we've not received a port
                     # number from the worker. This just prints out the error
                     # message and stacktrace that have come from the worker
@@ -367,15 +379,16 @@ end
 
 # The entire `src` dir should be relocatable, so that worker.jl can include("MsgType.jl").
 const startup_file = RelocatableFolders.@path joinpath(@__DIR__, "startup.jl")
+const empty_file = RelocatableFolders.@path joinpath(@__DIR__, "empty.jl")
 const worker_package = RelocatableFolders.@path joinpath(@__DIR__, "QuartoNotebookWorker")
 
-function _get_worker_cmd(; exe, env, exeflags)
+function _get_worker_cmd(; exe, env, exeflags, file = String(startup_file))
     defaults = Dict(
         "OPENBLAS_NUM_THREADS" => "1",
         "QUARTONOTEBOOKWORKER_PACKAGE" => String(worker_package),
     )
     env = vcat(Base.byteenv(defaults), Base.byteenv(env))
-    return addenv(`$exe --startup-file=no $exeflags $(String(startup_file))`, env)
+    return addenv(`$exe --startup-file=no $exeflags $file`, env)
 end
 
 # Checks whether a `julia` command (including it's program flags and juliaup

src/empty.jl

@@ -0,0 +1 @@
+

src/server.jl

@@ -51,8 +51,16 @@ function _julia_exe(exeflags)
     if all(!isnothing, Sys.which.(("juliaup", "julia")))
         indices = findall(startswith("+"), exeflags)
         if isempty(indices)
-            # Use the default `julia` channel set for `juliaup`.
-            return `julia`, exeflags
+            quarto_julia = get(ENV, "QUARTO_JULIA", nothing)
+            if isnothing(quarto_julia)
+                # Use the default `julia` channel set for `juliaup`.
+                return `julia`, exeflags
+            else
+                # Use the `julia` binary that was specified in the environment
+                # variable that can be passed to `quarto` to pick the server
+                # process `julia` to use.
+                return `$quarto_julia`, exeflags
+            end
         else
             # Pull out the channel from the exeflags. Since we merge in
             # exeflags from the `QUARTONOTEBOOKRUNNER_EXEFLAGS` environment