SSE DJANGO REQUEST COUNT

Question

i still new using SSE and i have a question about SSE in Django version 3.2.5, i am using StreamingHttpResponse to send SSE response to EventSource client and it does work fine, my question that

why it takes to long to open the connection between backend and EventSource?

why it sends only 167 responses/32 seconds ?

i tried to open the code of StreamingHttpResponse but i didn't find anything related to the number of response

here in the code

def sse_movies(request):
  def event_stream():
      while True:
          sleep(.2)
          yield f"data: {datetime.time(datetime.now())}\n\n"
  return StreamingHttpResponse(event_stream(), content_type='text/event-stream')

i am using sleep() to wait only 200/milliseconds for each iteration. but whenever send the EventSource it waits almost 32/seconds to initiate the connection with the back-end, and after it sends 167 requests then waits 2 seconds then sends another 167 requests once more and after the second 167 is sent it waits another 32 seconds

here is the code of EventSource client

    let url = '/test/' +'sse/movies/'
    let sse_client = new EventSource(url)
    let movies = document.querySelector('#data-movies')
    let movies_list = document.querySelector('#messages')

    sse_client.onopen  = function(message_event) {
        console.log('opened')
    }
    console.log(sse_client)

    sse_client.onmessage =  (message_event) => {
        console.log(message_event.data)
        console.log(sse_client.readyState)
}

NOTE: when i remove white: True EventSource doesn't wait and sends requests as much as possible

maybe i misunderstand something here, but i hope the somebody could help me

`.2` is not 2 milliseconds, it's 200 milliseconds or 1/5th of a second. Still doesn't explain much, but just wanted to note it — Alexandr Tatarinov, Aug 01 '21 at 12:55
@AlexandrTatarinov, Thanks for your explanation. i am still trying to figure it out but, still can't — Ahmed ELMawrdy, Aug 01 '21 at 13:11

Ahmed ELMawrdy · Accepted Answer · 2021-08-02T09:01:55.470

i could figure out the issue.

it was n't in the code itself, but it was related with the buffer size of the webserver

so when i edited my code to be as below it worked fine:

def sse_movies(request):
  def event_stream():
      body =  ''.join([letter * 6000 for letter in 'A'])
      body_len = len(body)
      print(body_len)

      while True:
          sleep(2)
          yield f"data: {body}\n\n"
  return StreamingHttpResponse(event_stream(), content_type='text/event-stream')

as you see above the minimum size for buffer is 6000/Characters i don't not how much that could be in bytes), but yeah it worked Alhumdulliah)

i really don't know that much about buffer/buffer-size/.. but i thought that it could be the issue

SSE DJANGO REQUEST COUNT

1 Answers1