--- old/src/share/vm/logging/logStream.cpp	2017-07-19 17:21:41.237259100 +0200
+++ new/src/share/vm/logging/logStream.cpp	2017-07-19 17:21:40.282714500 +0200
@@ -53,7 +53,8 @@
       return;
     }
 
-    size_t newcap = align_up(atleast + 64, 64);
+    const size_t additional_expansion = 256;
+    size_t newcap = align_up(atleast + additional_expansion, additional_expansion);
     if (newcap > reasonable_max) {
       log_info(logging)("Suspiciously long log line: \"%.100s%s",
               _buf, (_pos >= 100 ? "..." : ""));
@@ -79,11 +80,12 @@
 void LogStream::LineBuffer::append(const char* s, size_t len) {
   assert(_buf[_pos] == '\0', "sanity");
   assert(_pos < _cap, "sanity");
-  try_ensure_cap(_pos + len + 1);
+  const size_t minimum_capacity_needed = _pos + len + 1;
+  try_ensure_cap(minimum_capacity_needed);
   // try_ensure_cap may not have enlarged the capacity to the full requested
   // extend or may have not worked at all. In that case, just gracefully work
   // with what we have already; just truncate if necessary.
-  if (_pos + len + 1 > _cap) {
+  if (_cap < minimum_capacity_needed) {
     len = _cap - _pos - 1;
     if (len == 0) {
       return;
@@ -102,7 +104,7 @@
 void LogStream::write(const char* s, size_t len) {
   if (len > 0 && s[len - 1] == '\n') {
     _current_line.append(s, len - 1); // omit the newline.
-    _log_handle.print("%s", _current_line.ptr());
+    _log_handle.print("%s", _current_line.buffer());
     _current_line.reset();
   } else {
     _current_line.append(s, len);