Change max batch to one

src/http_handler.hpp

@@ -103,10 +103,12 @@ struct HttpHandler : ConnectionHandler {
     });
     stage0Thread = std::thread{[this]() {
       pthread_setname_np(pthread_self(), "stage-0");
+      int nulls = 0;
       for (;;) {
-        auto guard = pipeline.acquire<0, 0>();
+        auto guard = pipeline.acquire<0, 0>(1);
         for (auto &c : guard.batch) {
-          if (!c) {
+          nulls += !c;
+          if (nulls == 2) {
             return;
           }
           for (volatile int i = 0; i < loopIterations; i = i + 1)