def logstr(self):
        """handler the log records to formatted string"""

        result = []
        formater = LogFormatter(color=False)
        for record in self.logs:
            if isinstance(record, six.string_types):
                result.append(pretty_unicode(record))
            else:
                if record.exc_info:
                    a, b, tb = record.exc_info
                    tb = hide_me(tb, globals())
                    record.exc_info = a, b, tb
                result.append(pretty_unicode(formater.format(record)))
                result.append(u'\n')
        return u''.join(result)
handler the log records to formatted string
pyspider/processor/processor.py