Index: clangd/Trace.cpp
===================================================================
--- clangd/Trace.cpp
+++ clangd/Trace.cpp
@@ -151,6 +151,7 @@
     Event["ph"] = Phase;
     Out << Sep << formatv(JSONFormat, json::Value(std::move(Event)));
     Sep = ",\n";
+    Out.flush();
   }
 
   // If we haven't already, emit metadata describing this thread.