Avoid treating WAL senders as normal backends.

The previous coding treated anything that wasn't an autovacuum launcher
as a normal backend, which is wrong now that we also have WAL senders.

Fujii Masao, reviewed by Robert Haas, Alvaro Herrera, Tom Lane,
and Bernd Helmle.

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 179048f32d16ef6af08207b51018b6291c748d86..8f77d1bfc9754433b971cafcbd6c628cd3f4b347 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -3167,13 +3167,25 @@ SignalSomeChildren(int signal, int target)
 
        if (bp->dead_end)
            continue;
-       if (!(target & BACKEND_TYPE_NORMAL) && !bp->is_autovacuum)
-           continue;
-       if (!(target & BACKEND_TYPE_AUTOVAC) && bp->is_autovacuum)
-           continue;
-       if (!(target & BACKEND_TYPE_WALSND) &&
-           IsPostmasterChildWalSender(bp->child_slot))
-           continue;
+
+       /*
+        * Since target == BACKEND_TYPE_ALL is the most common case,
+        * we test it first and avoid touching shared memory for
+        * every child.
+        */
+       if (target != BACKEND_TYPE_ALL)
+       {
+           int         child;
+
+           if (bp->is_autovacuum)
+               child = BACKEND_TYPE_AUTOVAC;
+           else if (IsPostmasterChildWalSender(bp->child_slot))
+               child = BACKEND_TYPE_WALSND;
+           else
+               child = BACKEND_TYPE_NORMAL;
+           if (!(target & child))
+               continue;
+       }
 
        ereport(DEBUG4,
                (errmsg_internal("sending signal %d to process %d",
@@ -4380,13 +4392,25 @@ CountChildren(int target)
 
        if (bp->dead_end)
            continue;
-       if (!(target & BACKEND_TYPE_NORMAL) && !bp->is_autovacuum)
-           continue;
-       if (!(target & BACKEND_TYPE_AUTOVAC) && bp->is_autovacuum)
-           continue;
-       if (!(target & BACKEND_TYPE_WALSND) &&
-           IsPostmasterChildWalSender(bp->child_slot))
-           continue;
+
+       /*
+        * Since target == BACKEND_TYPE_ALL is the most common case,
+        * we test it first and avoid touching shared memory for
+        * every child.
+        */
+       if (target != BACKEND_TYPE_ALL)
+       {
+           int         child;
+
+           if (bp->is_autovacuum)
+               child = BACKEND_TYPE_AUTOVAC;
+           else if (IsPostmasterChildWalSender(bp->child_slot))
+               child = BACKEND_TYPE_WALSND;
+           else
+               child = BACKEND_TYPE_NORMAL;
+           if (!(target & child))
+               continue;
+       }
 
        cnt++;
    }