fix(bigtable): fix a nil pointer deference in remove connections when… (#13535)

sushanb · web-flow · commit 9d2ba82ecd77 · 2026-01-05T14:09:17.000-05:00
… one conn is being drained
diff --git a/bigtable/internal/transport/connpool.go b/bigtable/internal/transport/connpool.go
@@ -830,11 +830,11 @@ func (p *BigtableChannelPool) removeConnections(decreaseDelta, minConns, maxRemo
 		return false
 	}
 
-	entries := make([]entryWithAge, numSnapshot)
-	for i, entry := range snapshotConns {
+	entries := make([]entryWithAge, 0, numSnapshot)
+	for _, entry := range snapshotConns {
 		// Only consider connections not *already* draining for removal via this logic.
 		if !entry.isDraining() {
-			entries[i] = entryWithAge{entry: entry, createdAt: entry.conn.creationTime()}
+			entries = append(entries, entryWithAge{entry: entry, createdAt: entry.conn.creationTime()})
 		}
 	}
 
diff --git a/bigtable/internal/transport/connpool_test.go b/bigtable/internal/transport/connpool_test.go
@@ -1417,6 +1417,29 @@ func TestRemoveConnections(t *testing.T) {
 			}
 		}
 	})
+
+	t.Run("MixedDrainingState", func(t *testing.T) {
+		poolSize := 5
+		pool, err := NewBigtableChannelPool(ctx, poolSize, btopt.RoundRobin, dialFunc, poolOpts()...)
+		if err != nil {
+			t.Fatalf("Failed to create pool: %v", err)
+		}
+		defer pool.Close()
+
+		conns := pool.getConns()
+		conns[2].markAsDraining()
+
+		changed := pool.removeConnections(1, 1, 5)
+
+		if !changed {
+			t.Errorf("Expected pool change, got false")
+		}
+		finalConns := pool.getConns()
+
+		if len(finalConns) != 3 {
+			t.Errorf("Expected final size 3, got %d", len(finalConns))
+		}
+	})
 }
 
 func TestConnPoolStatisticsVisitor(t *testing.T) {

Original file line number	Diff line number	Diff line change
`@@ -830,11 +830,11 @@ func (p *BigtableChannelPool) removeConnections(decreaseDelta, minConns, maxRemo`
`830`	`830`	`return false`
`831`	`831`	`}`
`832`	`832`
`833`		`- entries := make([]entryWithAge, numSnapshot)`
`834`		`- for i, entry := range snapshotConns {`
	`833`	`+ entries := make([]entryWithAge, 0, numSnapshot)`
	`834`	`+ for _, entry := range snapshotConns {`
`835`	`835`	`// Only consider connections not already draining for removal via this logic.`
`836`	`836`	`if !entry.isDraining() {`
`837`		`- entries[i] = entryWithAge{entry: entry, createdAt: entry.conn.creationTime()}`
	`837`	`+ entries = append(entries, entryWithAge{entry: entry, createdAt: entry.conn.creationTime()})`
`838`	`838`	`}`
`839`	`839`	`}`
`840`	`840`