Revert the suspicious change (the last non-comment change) in the past PR

Author: HyukjinKwon

R/pkg/inst/worker/daemon.R

@@ -33,9 +33,6 @@ inputCon <- socketConnection(
 # Waits indefinitely for a socket connecion by default.
 selectTimeout <- NULL
 
-# Exit code that children send to the parent to indicate they exited.
-exitCode <- 1
-
 while (TRUE) {
   ready <- socketSelect(list(inputCon), timeout = selectTimeout)
 
@@ -62,18 +59,7 @@ while (TRUE) {
   children <- parallel:::selectChildren(timeout = 0)
 
   if (is.integer(children)) {
-    lapply(children, function(child) {
-      # This data should be raw bytes if any data was sent from this child.
-      # Otherwise, this returns the PID.
-      data <- parallel:::readChild(child)
-      if (is.raw(data)) {
-        # This checks if the data from this child is the exit code that indicates an exited child.
-        if (unserialize(data) == exitCode) {
-          # If so, we terminate this child.
-          tools::pskill(child, tools::SIGUSR1)
-        }
-      }
-    })
+    lapply(children, function(child) { tools::pskill(child, tools::SIGUSR1) })
   } else if (is.null(children)) {
     # If it is NULL, there are no children. Waits indefinitely for a socket connecion.
     selectTimeout <- NULL
@@ -97,7 +83,7 @@ while (TRUE) {
       try(source(script))
       # Note that this mcexit does not fully terminate this child. So, this writes back
       # a custom exit code so that the parent can read and terminate this child.
-      parallel:::mcexit(0L, send = exitCode)
+      parallel:::mcexit(0L)
     } else {
       # Forking succeeded and we need to check if they finished their jobs every second.
       selectTimeout <- 1