chore: partially revert adjust batching behavior to reduce network (#…

…1821)

* partially reverts #1777

src/facade/dragonfly_connection.cc

@@ -799,28 +799,12 @@ void Connection::DispatchFiber(util::FiberSocketBase* peer) {
 
   size_t squashing_threshold = absl::GetFlag(FLAGS_pipeline_squash);
 
-  uint64_t prev_epoch = fb2::FiberSwitchEpoch();
   while (!builder->GetError()) {
     evc_.await(
         [this] { return cc_->conn_closing || (!dispatch_q_.empty() && !cc_->sync_dispatch); });
     if (cc_->conn_closing)
       break;
 
-    // We really want to have batching in the builder if possible. This is especially
-    // critical in situations where Nagle's algorithm can introduce unwanted high
-    // latencies. However we can only batch if we're sure that there are more commands
-    // on the way that will trigger a flush. To know if there are, we sometimes yield before
-    // executing the last command in the queue and let the producer fiber push more commands if it
-    // wants to.
-    // As an optimization, we only yield if the fiber was not suspended since the last dispatch.
-    uint64_t cur_epoch = fb2::FiberSwitchEpoch();
-    if (dispatch_q_.size() == 1 && cur_epoch == prev_epoch) {
-      ThisFiber::Yield();
-      DVLOG(1) << "After yielding to producer, dispatch_q_.size()=" << dispatch_q_.size();
-    }
-    prev_epoch = cur_epoch;
-    builder->SetBatchMode(dispatch_q_.size() > 1);
-
     auto recycle = [this, request_cache_limit](MessageHandle msg) {
       dispatch_q_bytes_.fetch_sub(msg.UsedMemory(), memory_order_relaxed);
 
@@ -834,6 +818,8 @@ void Connection::DispatchFiber(util::FiberSocketBase* peer) {
       }
     };
 
+    builder->SetBatchMode(dispatch_q_.size() > 1);
+
     // Special case: if the dispatch queue accumulated a big number of commands,
     // we can try to squash them
     // It is only enabled if the threshold is reached and the whole dispatch queue