Multiple async calls get mixed up

[thehunmonkgroup]

I use the utility function listed below to make individual API calls via this package, with FS as an instance of esl.client():

FreeswitchUtil.prototype.runFreeswitchCommand = function(command, callback, FS) {
  callback = callback ? callback : function() {};
  FS = FS ? FS : this.FS;
  this.logger.debug(format("Running command '%s'", command));
  FS.api(command)
  .then(function(res) {
    this.logger.debug(format("Command '%s' result headers: %s", command, JSON.stringify(res.headers)));
    this.logger.debug(format("Command '%s' result body: %s", command, res.body));
    callback(null, res.body);
  }.bind(this))
  .catch(function(error) {
    if (_.isObject(error.res)) {
      this.logger.error(format("Command '%s' error: %s", command, error.res.body));
      callback(error.res.body, null);
    }
    else {
      this.logger.error(format("Command '%s' error: %s", command, JSON.stringify(error)));
      callback(error, null);
    }
  }.bind(this));
}

When I put the system under load with a lot of async calls happening, I see logging output that looks like certain commands get overwritten by other incoming commands:

debug: Command 'conference 585 vid-res-id 18 3' result body: Non-Existant ID 15

The ID in that response should not be 15, as I'm sending 18 in the command. The command variable is scoped to my function, so it doesn't make any sense to me that it's getting overwritten in the function itself.

Curious if I've set things up wrong in my support function, or if this package has some issue handling lots of simultaneous calls, or if it's some bug in FreeSWITCH?

FYI, running version 4.0.1 of this package, as it seems to be the newest that runs on node 10.x

[shimaore]

The mixing-up of commands in client mode is a known issue in 4.x which has been mitigated in 5.x.

[thehunmonkgroup]

I don't supposed that fix can be backported to 4.x, or 5.x made to work with node 10.x?

The latter is probably better, as some major distributions still have 10.x in their packaging systems. I did make a first try at fixing 5.x for node 10.x, but wasn't able to get it working.