扭曲的Web服务器处理请求多次

Question

我已经从官方站点复制了扭曲Web服务器的示例。代码如下：

from twisted.web import server, resource
from twisted.internet import reactor, endpoints

class Counter(resource.Resource):
    isLeaf = True
    numberRequests = 0

    def render_GET(self, request):
        self.numberRequests += 1
        request.setHeader(b"content-type", b"text/plain")
        content = u"I am request #{}\n".format(self.numberRequests)
        return content.encode("ascii")

endpoints.serverFromString(reactor, "tcp:8080").listen(server.Site(Counter()))
reactor.run()

当我在8080上发送请求时，输出为：

I am request #1
I am request #3
I am request #5

应该是：

I am request #1
I am request #2
I am request #3

这是为什么？