diff --git a/mypy/dmypy/client.py b/mypy/dmypy/client.py
index 0e9120608509..c3a2308d1b44 100644
--- a/mypy/dmypy/client.py
+++ b/mypy/dmypy/client.py
@@ -562,6 +562,7 @@ def check_output(
     sys.stdout.write(out)
     sys.stdout.flush()
     sys.stderr.write(err)
+    sys.stderr.flush()
     if verbose:
         show_stats(response)
     if junit_xml:
@@ -588,13 +589,14 @@ def check_output(
 
 def show_stats(response: Mapping[str, object]) -> None:
     for key, value in sorted(response.items()):
-        if key not in ("out", "err"):
-            print("%-24s: %10s" % (key, "%.3f" % value if isinstance(value, float) else value))
-        else:
+        if key in ("out", "err", "stdout", "stderr"):
+            # Special case text output to display just 40 characters of text
             value = repr(value)[1:-1]
             if len(value) > 50:
-                value = value[:40] + " ..."
+                value = f"{value[:40]} ... {len(value)-40} more characters"
             print("%-24s: %s" % (key, value))
+            continue
+        print("%-24s: %10s" % (key, "%.3f" % value if isinstance(value, float) else value))
 
 
 @action(hang_parser)
@@ -668,6 +670,8 @@ def request(
     # TODO: Other errors, e.g. ValueError, UnicodeError
     else:
         # Display debugging output written to stdout/stderr in the server process for convenience.
+        # This should not be confused with "out" and "err" fields in the response.
+        # Those fields hold the output of the "check" command, and are handled in check_output().
         stdout = response.get("stdout")
         if stdout:
             sys.stdout.write(stdout)