test multithreaded logging

Author: IanButterworth

stdlib/Logging/test/runtests.jl

@@ -306,4 +306,14 @@ end
     @test isempty(undoc)
 end
 
+@testset "thread safety" begin
+    cmd = `$(Base.julia_cmd()) -t4 $(joinpath(@__DIR__, "threads_exec.jl"))`
+    fname = tempname()
+    f = open(fname, "w")
+    redirect_stderr(f) do
+        success(run(cmd))
+    end
+    close(f)
+end
+
 end

stdlib/Logging/test/threads_exec.jl

@@ -0,0 +1,13 @@
+using Logging
+
+function test_threads_exec(n)
+    Threads.@threads for i in 1:n
+        x = rand()
+        @debug "iteration" i x Threads.threadid()
+        @info "iteration" i x Threads.threadid()
+        @warn "iteration" i x Threads.threadid()
+        @error "iteration" i x Threads.threadid()
+    end
+end
+
+test_threads_exec(100000)