add pid to test logs under rr (JuliaLang#39577)

Should make starting replay much easier

test/runtests.jl

@@ -13,6 +13,15 @@ include("testenv.jl")
 tests, net_on, exit_on_error, use_revise, seed = choosetests(ARGS)
 tests = unique(tests)
 
+if Sys.islinux()
+    const SYS_rrcall_check_presence = 1008
+    global running_under_rr() = 0 == ccall(:syscall, Int,
+        (Int, Int, Int, Int, Int, Int, Int),
+        SYS_rrcall_check_presence, 0, 0, 0, 0, 0, 0)
+else
+    global running_under_rr() = false
+end
+
 if use_revise
     using Revise
     union!(Revise.stdlib_names, Symbol.(STDLIBS))
@@ -137,17 +146,22 @@ cd(@__DIR__) do
         finally
             unlock(print_lock)
         end
+        nothing
     end
 
     global print_testworker_started = (name, wrkr)->begin
+        pid = running_under_rr() ? remotecall_fetch(getpid, wrkr) : 0
+        at = lpad("($wrkr)", name_align - textwidth(name) + 1, " ")
         lock(print_lock)
         try
-            printstyled(name, color=:white)
-            printstyled(lpad("($wrkr)", name_align - textwidth(name) + 1, " "), " |",
-                " "^elapsed_align, "started at $(now())\n", color=:white)
+            printstyled(name, at, " |", " "^elapsed_align,
+                    "started at $(now())",
+                    (pid > 0 ? " on pid $pid" : ""),
+                    "\n", color=:white)
         finally
             unlock(print_lock)
         end
+        nothing
     end
 
     function print_testworker_errored(name, wrkr, @nospecialize(e))

test/threads.jl

@@ -11,12 +11,11 @@ let cmd = `$(Base.julia_cmd()) --depwarn=error --rr-detach --startup-file=no thr
 end
 
 # issue #34415 - make sure external affinity settings work
-const SYS_rrcall_check_presence = 1008
-running_under_rr() = 0 == ccall(:syscall, Int,
-    (Int, Int, Int, Int, Int, Int, Int),
-    SYS_rrcall_check_presence, 0, 0, 0, 0, 0, 0)
-
 if Sys.islinux()
+    const SYS_rrcall_check_presence = 1008
+    global running_under_rr() = 0 == ccall(:syscall, Int,
+        (Int, Int, Int, Int, Int, Int, Int),
+        SYS_rrcall_check_presence, 0, 0, 0, 0, 0, 0)
     if Sys.CPU_THREADS > 1 && Sys.which("taskset") !== nothing && !running_under_rr()
         run_with_affinity(spec) = readchomp(`taskset -c $spec $(Base.julia_cmd()) -e "run(\`taskset -p \$(getpid())\`)"`)
         @test endswith(run_with_affinity("1"), "2")