Set a 1,000 block validation backlog.

src/chasers/chaser_validate.cpp

@@ -152,14 +152,17 @@ void chaser_validate::do_checked(height_t height) NOEXCEPT
         do_bump(height);
 }
 
+constexpr auto validation_window = 1'000_size;
+
 void chaser_validate::do_bump(height_t) NOEXCEPT
 {
     BC_ASSERT(stranded());
     const auto& query = archive();
 
     // Validate checked blocks starting immediately after last validated.
     // Bypass until next event if validation backlog is full.
-    for (auto height = add1(position()); !closed(); ++height)
+    for (auto height = add1(position());
+        (validation_backlog_ < validation_window) && !closed(); ++height)
     {
         const auto link = query.to_candidate(height);
         const auto ec = query.get_block_state(link);
@@ -268,6 +271,10 @@ void chaser_validate::complete_block(const code& ec, const header_link& link,
     // Trigger confirmation now that validations are current.
     if (is_current(link))
         notify(ec, chase::valid, possible_wide_cast<height_t>(height));
+
+    // Prevent stall when window was full.
+    if (validation_backlog_ == sub1(validation_window))
+        do_bump(height_t{});
 }
 
 // neutrino