The second log record should be the handler output of the root logger. By default, the log will be processed between handlers and bubble up to the upper layer.
The following is the code for logging callHandlers. callHandlers的代码。

c = self
found = 0
while c:
    for hdlr in c.handlers:
        found = found + 1
        if record.levelno >= hdlr.level:
            hdlr.handle(record)
    if not c.propagate:
        c = None    #break out
    else:
        c = c.parent
        

找到输出第一条日志的logger对象，设置 logger.propagate = 0 rrreee