I tried to use syslog-ng.

At first I used a syslog-ng 3.5.3 on ubuntu14.04.

But I can not use flush_line option.

I asked question in stack overflow.

Mr.argus said that " There is a lack of condition"

linux - syslog-ng の flush_lines　オプションが効かない - スタック・オーバーフロー

Specifically function "log_writer_flush" should be like that.

Before:

gboolean
log_writer_flush(LogWriter *self, LogWriterFlushMode flush_mode)
{
                       :

  if (flush_mode >= LW_FLUSH_BUFFER || count == 0)
  {
    if (log_proto_client_flush(proto) == LPS_ERROR)
      return FALSE;
  }

After:

LogProtoFileWriter *w = (LogProtoFileWriter *)proto;
if ( (w->buf_count >= w->buf_size) && (flush_mode >= LW_FLUSH_BUFFER || count == 0) )
  {
    if (log_proto_client_flush(proto) == LPS_ERROR)
      return FALSE;
  }

And now I use a latest syslog-ng ose 3.7.1, hoping the bug has been fixed.

But I can not use flush_line option either.

Is the option flush_lines valid now?