为什么Flask Python无法流式传输数据

服务器端:

from flask import Flask, request, Response, stream_with_context
import time

app = Flask(__name__)

# Define a route /stream that handles POST requests
@app.route('/stream', methods=['POST'])  # GET also been tried, no difference
def stream():
    @stream_with_context
    def generate():
        print('1')
        yield "Hello\n"
        time.sleep(1) # Simulate some delay
        print('2')
        yield "World\n"
        time.sleep(1)
        print('3')
        yield "This is\n"
        time.sleep(1)
        print('4')
        yield "Streaming data\n"
        time.sleep(1)
        print('5')

    return Response(generate(), content_type='text/event-stream')

if __name__ == '__main__':
    app.run(debug=True)

客户端:

import requests
import sseclient

reqUrl = 'https://api.my-domain-name.com/stream'
headers={'Accept': 'text/event-stream'} 


# response = requests.get(url=reqUrl, headers=headers, stream=True)
response = requests.post(url=reqUrl, headers=headers, stream=True)

if response.status_code == 200:
    for chunk in response.iter_content(chunk_size=3):
        if chunk:
            print(chunk)
else:
    print('fail:', response.status_code)

# sse tried, no difference
# client = sseclient.SSEClient(response)
# for event in client.events():
#     print(event.data)

When client connected, there was 1 2 3 4 5 printed one by one at the server side.
But client printed nothing, until server finished, client printed all data. Help!

我已经try 了上面的代码，并try 了GET/POST，无论是否使用SSE. 当我try GET方法时，我也try 了curl-v命令，同样的结果，数据在大约5秒后聚集在一起，而不是一个接一个. 我预计流数据，即每个yield 率数据都可以单独及时处理，而不是一起处理.