--- old/test/hotspot/gtest/logging/test_logMessageTest.cpp	2020-02-24 07:47:46.841117556 +0000
+++ new/test/hotspot/gtest/logging/test_logMessageTest.cpp	2020-02-24 07:47:46.581116130 +0000
@@ -215,6 +215,39 @@
     << "error in prefixed output";
 }
 
+TEST_VM_F(LogMessageTest, nwrite) {
+  const char* msg = "The quick brown fox jumps over the lazy dog";
+  const char* msg2 = "test-without-prefix";
+  Arena* arena = new (mtLogging)Arena(mtLogging);
+  LogMessageBuffer buf(arena);
+
+  buf.set_prefix(dummy_prefixer);
+  size_t len = strlen(msg);
+  // keep writing until reallocation
+  while (buf._message_buffer_size
+    < LogMessageBuffer::InitialMessageBufferCapacity * 3) {
+    buf.write_n(LogLevel::Trace, msg, len);
+  }
+
+  buf.set_prefix(NULL);
+  len = strlen(msg2);
+  buf.write_n(LogLevel::Trace, msg2, len);
+  _log.write(buf);
+
+  const char* expected[] = {
+    "] some prefix: The quick brown fox jumps over the lazy dog",
+    "] some prefix: The quick brown fox jumps over the lazy dog",
+    "] some prefix: The quick brown fox jumps over the lazy dog",
+    "] test-without-prefix",
+    NULL
+  };
+
+  EXPECT_TRUE(file_contains_substrings_in_order(_level_filename[LogLevel::Trace], expected))
+    << "error in prefixed output";
+
+  delete arena;
+}
+
 TEST_VM_F(LogMessageTest, scoped_messages) {
   {
     LogMessage(logging) msg;