Issue 19960 - loading module on remote workers

base/loading.jl

@@ -218,8 +218,14 @@ function _require_search_from_serialized(node::Int, mod::Symbol, sourcepath::Str
  end
 
  for path_to_try in paths::Vector{String}
- if stale_cachefile(sourcepath, path_to_try)
- continue
+ if node == myid()
+ if stale_cachefile(sourcepath, path_to_try)
+ continue
+ end
+ else
+ if @fetchfrom node stale_cachefile(sourcepath, path_to_try)
+ continue
+ end
  end
  restored = _require_from_serialized(node, mod, path_to_try, toplevel_load)
  if isa(restored, Exception)

test/compile.jl

@@ -524,4 +524,55 @@ let module_name = string("a",randstring())
  rm(file_name)
 end
 
+# Issue #19960
+let
+ # ideally this would test with workers on a remote host that does not have access to the master node filesystem for loading
+ # can simulate this for local workers by using relative load paths on master node that are not valid on workers
+ # so addprocs before changing directory to temp directory, otherwise workers will inherit temp working directory
+
+ test_workers = addprocs(1)
+ temp_path = mktempdir()
+ save_cwd = pwd()
+ cd(temp_path)
+ load_path = mktempdir(temp_path)
+ load_cache_path = mktempdir(temp_path)
+ unshift!(LOAD_PATH, basename(load_path))
+ unshift!(Base.LOAD_CACHE_PATH, basename(load_cache_path))
+
+ ModuleA = :Issue19960A
+ ModuleB = :Issue19960B
+
+ write(joinpath(load_path, "$ModuleA.jl"),
+ """
+ __precompile__(true)
+ module $ModuleA
+ export f
+ f() = myid()
+ end
+ """)
+
+ write(joinpath(load_path, "$ModuleB.jl"),
+ """
+ __precompile__(true)
+ module $ModuleB
+ using $ModuleA
+ export g
+ g() = f()
+ end
+ """)
+
+ try
+ @eval using $ModuleB
+ for wid in test_workers
+ @test remotecall_fetch(g, wid) == wid
+ end
+ finally
+ shift!(LOAD_PATH)
+ shift!(Base.LOAD_CACHE_PATH)
+ cd(save_cwd)
+ rm(temp_path, recursive=true)
+ rmprocs(test_workers)
+ end
+end
+
 end # !withenv