From bc39fa234dd2d2834985dcdd37159cbc9e4d8a51 Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang.org>
Date: Mon, 15 Apr 2019 17:02:32 +0200
Subject: erts: Yield correctly when iterating over distr exit messages

Before this fix the process would continue to process
more distributed down or exit messages until it
ran out of reductions instead of being suspended
immediately.
---
 erts/emulator/beam/erl_process.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

(limited to 'erts/emulator/beam')

diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 2b45d2d353..76eec96372 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -12095,6 +12095,7 @@ erts_proc_exit_handle_dist_monitor(ErtsMonitor *mon, void *vctxt, Sint reds)
     Eterm watched;
     Uint watcher_sz, ref_sz;
     ErtsHeapFactory factory;
+    Sint reds_consumed = 0;
 
     ASSERT(erts_monitor_is_target(mon) && mon->type == ERTS_MON_TYPE_DIST_PROC);
 
@@ -12139,11 +12140,13 @@ erts_proc_exit_handle_dist_monitor(ErtsMonitor *mon, void *vctxt, Sint reds)
                                      watched,
                                      ref,
                                      reason);
+        reds_consumed = reds - (ctx.reds / TERM_TO_BINARY_LOOP_FACTOR);
         switch (code) {
         case ERTS_DSIG_SEND_CONTINUE:
         case ERTS_DSIG_SEND_YIELD:
             erts_set_gc_state(c_p, 0);
             ctxt->dist_state = erts_dsend_export_trap_context(c_p, &ctx);
+            reds_consumed = reds; /* force yield */
             break;
         case ERTS_DSIG_SEND_OK:
             break;
@@ -12163,7 +12166,7 @@ erts_proc_exit_handle_dist_monitor(ErtsMonitor *mon, void *vctxt, Sint reds)
         erts_monitor_release(mon);
     else
         erts_monitor_release_both(mdp);
-    return reds - (ctx.reds / TERM_TO_BINARY_LOOP_FACTOR);
+    return reds_consumed;
 }
 
 int
@@ -12350,6 +12353,7 @@ erts_proc_exit_handle_dist_link(ErtsLink *lnk, void *vctxt, Sint reds)
     ErtsLink *dlnk;
     ErtsLinkData *ldp = NULL;
     ErtsHeapFactory factory;
+    Sint reds_consumed = 0;
 
     ASSERT(lnk->type == ERTS_LNK_TYPE_DIST_PROC);
     dlnk = erts_link_to_other(lnk, &ldp);
@@ -12386,11 +12390,13 @@ erts_proc_exit_handle_dist_link(ErtsLink *lnk, void *vctxt, Sint reds)
                                       item,
                                       reason,
                                       SEQ_TRACE_TOKEN(c_p));
+        reds_consumed = reds - (ctx.reds / TERM_TO_BINARY_LOOP_FACTOR);
         switch (code) {
         case ERTS_DSIG_SEND_YIELD:
         case ERTS_DSIG_SEND_CONTINUE:
             erts_set_gc_state(c_p, 0);
             ctxt->dist_state = erts_dsend_export_trap_context(c_p, &ctx);
+            reds_consumed = reds; /* force yield */
             break;
         case ERTS_DSIG_SEND_OK:
             break;
@@ -12410,7 +12416,7 @@ erts_proc_exit_handle_dist_link(ErtsLink *lnk, void *vctxt, Sint reds)
         erts_link_release_both(ldp);
     else if (lnk)
         erts_link_release(lnk);
-    return reds - (ctx.reds / TERM_TO_BINARY_LOOP_FACTOR);
+    return reds_consumed;
 }
 
 int
-- 
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