fetch hangs indefinitely during second request to a certain webpage when using HTTP/2 #3433

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1. marvinruder

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   bugSomething isn't workingSomething isn't working

   on Aug 2, 2024
2. KhafraDev commented on Aug 2, 2024

   

   KhafraDev

   on Aug 2, 2024

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   @metcoder95

   👀React with 👀1Reacted by Carlos Fuentes
3. metcoder95 commented on Aug 4, 2024

   

   metcoder95

   on Aug 4, 2024

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   Hi @marvinruder,

   After debugging the use case you shared, I can tell you that this is a somehow expected behavior given the current design of the Agent.

   What is happening is that, as the connection is not a keep-alive, the server immediately after a second, sends a GOAWAY frame to the client, hinting to gracefully shutdown the connection with the remote origin.
   So, if you are able to trigger two or more requests within a timeframe of < 1s, they will be sent concurrently within the same connection as per H2 specification, but if waiting more than that time window the server immediately hints to close the connection.

   Sadly, this lefts the session unusable and it is needed to create a new connection from start with the remote origin. Currently this is not supported by the Agent class, but you can use a Pool instead. Maybe is detecting this network situations can be something nice to add to the Agent class.

   See following example for reproduction:

   const { setTimeout: sleep } = require('node:timers/promises')
   const { request, fetch, Agent } = require('undici')
   
   const agent = new Agent({ allowH2: true })
   const delay = process.env.DELAY ?? 1000
   
   fetch('https://www.marketscreener.com', { dispatcher: agent })
     .then(res => {
       console.log('1st request', res.status)
   
       return sleep(delay)
     })
     .then(() => {
       console.log('dispatching after sleep for', delay, 'ms')
       return fetch('https://www.marketscreener.com', { dispatcher: agent })
     })
     .then(res => {
       console.log('2nd request', res.status)
     })
     .catch(console.error)
4. marvinruder commented on Aug 9, 2024

   

   marvinruder

   on Aug 9, 2024

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   @metcoder95 Thanks for the detailed answer! It would be great if the Agent class was able to detect these cases one day. For the moment I will create short-lived H2 agents more frequently in my use case.

   👍React with 👍1Reacted by Carlos Fuentes
5. metcoder95 commented on Aug 12, 2024

   

   metcoder95

   on Aug 12, 2024

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   I'll close this issue as completed, but please feel free to open a new one for discussing this possible feature to the Agent class
6. metcoder95

   closed this as completedon Aug 12, 2024