fixup! [erts] Scheduler pollset migration only when single process enif_select

Author: sverker

erts/emulator/sys/common/erl_check_io.c

@@ -1253,6 +1253,7 @@ enif_select_x(ErlNifEnv* env,
     ErtsDrvSelectDataState *free_select = NULL;
     ErtsNifSelectDataState *free_nif = NULL;
     ErtsPollEvents new_events = 0;
+    const Eterm recipient = pid ? pid->pid : env->proc->common.id;
 #ifdef DEBUG_PRINT_MODE
     char tmp_buff[255];
 #endif
@@ -1345,6 +1346,8 @@ enif_select_x(ErlNifEnv* env,
     old_events = state->events;
 
     if (on) {
+        ASSERT(is_internal_pid(recipient));
+
         if (state->type == ERTS_EV_TYPE_NONE)
             ctl_op = ERTS_POLL_OP_ADD;
 #if ERTS_POLL_USE_SCHEDULER_POLLING
@@ -1356,10 +1359,9 @@ enif_select_x(ErlNifEnv* env,
                 /* Check if this is a different process than last time.
                  * If so, reset the counter to prevent scheduler pollset migration
                  * in multi-process scenarios (e.g., multiple socket:accept callers). */
-                Eterm current_pid = env->proc->common.id;
-                if (state->last_select_pid != current_pid) {
+                if (state->last_select_pid != recipient) {
                     state->count = 0;
-                    state->last_select_pid = current_pid;
+                    state->last_select_pid = recipient;
                 }
                 else if (++(state->count) > 10) {
                     int wake_poller = 0;
@@ -1436,8 +1438,6 @@ enif_select_x(ErlNifEnv* env,
 	   || state->type == ERTS_EV_TYPE_NONE);
 
     if (on) {
-        const Eterm recipient = pid ? pid->pid : env->proc->common.id;
-        ASSERT(is_internal_pid(recipient));
         if (!state->driver.nif)
             state->driver.nif = alloc_nif_select_data();
         if (state->type == ERTS_EV_TYPE_NONE) {