process received messages one at a time without sleeping between messages

src/main.cpp

@@ -3141,6 +3141,9 @@ void static ProcessGetData(CNode* pfrom)
 
             // Track requests for our stuff.
             Inventory(inv.hash);
+
+            if (inv.type == MSG_BLOCK || inv.type == MSG_FILTERED_BLOCK)
+                break;
         }
     }
 
@@ -3751,6 +3754,9 @@ bool ProcessMessages(CNode* pfrom)
     if (!pfrom->vRecvGetData.empty())
         ProcessGetData(pfrom);
 
+    // this maintains the order of responses
+    if (!pfrom->vRecvGetData.empty()) return fOk;
+
     std::deque<CNetMessage>::iterator it = pfrom->vRecvMsg.begin();
     while (!pfrom->fDisconnect && it != pfrom->vRecvMsg.end()) {
         // Don't bother if send buffer is too full to respond anyway
@@ -3841,6 +3847,8 @@ bool ProcessMessages(CNode* pfrom)
 
         if (!fRet)
             printf("ProcessMessage(%s, %u bytes) FAILED\n", strCommand.c_str(), nMessageSize);
+
+        break;
     }
 
     // In case the connection got shut down, its receive buffer was wiped