Plugin HTTP handler or Lambda not getting called, after triggering after_save with async=True

[Steven-Chan]

Skygear Server Date/Version: v0.22.1, python plugin with zmq

Steps to reproduce

1. client call save record
2. trigger after_save in plugin
3. client call http handler or lambda
4. the handler function is not called
5. plugin time out after a while

Methods to make the handler work:
either:

• use http instead of zmq
• set async=False

[Steven-Chan]

plugin:

import logging
import skygear

log = logging.getLogger(__name__)


@skygear.handler('handler', method=['POST'])
def handler(req):
    return {
        'result': 'handler is OK'
    }


@skygear.after_save('recordA', async=True)
def recordA_async_after_save(record, original_record, conn):
    log.info('recordA_async_after_save')

client.js

const skygear = require('skygear');
const agent = require('superagent');

const RecordA = skygear.Record.extend('recordA');

skygear.config({
  'apiKey': 'apikey',
  'endPoint': 'http://localhost:3000/',
}).then(() => {
  return skygear.signupAnonymously();
}).then(() => {
  const r = new RecordA({ 'content': 'Hello World' });
  return skygear.publicDB.save(r, {atomic: true});
}).then(() => {
  console.log('save success');
  agent.post('http://localhost:3000/handler').end((err, res) => {
    if (err) {
      console.log('http handler err');
    } else {
      console.log('http handler success');
    }
  });
}).catch(() => {
  console.log('save failed');
});

log:

save success

## after a while
http handler err

[b123400]

Cause identified.

ZMQ broker expect the response channel to be consumed.
zmqTransport does not always consume response channel.

When a request is ended before async handler responds, transport gives up consuming from broker. Broker keeps waiting for the channel to be consumed.

Working on a fix.

[chpapa]

@Steven-Chan Can you help verify the pull request fixed your issue? If yes please close it.

[rickmak]

Steven verified it is fixed.