Merge pull request #16095 from JuliaLang/amitm/detect_err_cause

Request to Test: detect cause of #16091

Author: tkelman

test/examples.jl

@@ -47,13 +47,37 @@ end
 dc_path = joinpath(dir, "dictchannel.jl")
 myid() == 1 || include(dc_path)
 
+# The checks to see if DictChannel is defined is to identify the root cause of
+# https://github.com/JuliaLang/julia/issues/16091 .
+# To be removed once fixed.
+defined_on_worker = false
+if (myid() != 1) && !isdefined(:DictChannel)
+    error("myid : $(myid()). DictChannel not defined.")
+else
+    defined_on_worker = true
+end
+
 # Run the remote on pid 1, since runtests may terminate workers
 # at any time depending on memory usage
-remotecall_fetch(1, dc_path) do f
+@test remotecall_fetch(1, dc_path) do f
     include(f)
-    nothing
+    return :infungible
+end === :infungible
+
+defined_on_master = false
+if remotecall_fetch(isdefined, 1, :DictChannel) == false
+    error("myid : $(myid()). DictChannel not defined on 1")
+else
+    defined_on_master = true
+end
+
+dc = nothing
+try
+    dc=RemoteChannel(()->DictChannel(), 1)
+catch e
+    println("myid : ", myid(), ", dc_path : ", dc_path, ", defined_on_worker:", defined_on_worker, ", defined_on_master: ", defined_on_master)
+    rethrow(e)
 end
-dc=RemoteChannel(()->DictChannel(), 1)
 @test typeof(dc) == RemoteChannel{DictChannel}
 
 @test isready(dc) == false