Develop Reference

Asynchronously stopping a loop from outside node.js

I am using node.js 14 and currently have a loop that is made by a recursive function and a setTimeout, something like this:
this.timer = null;
async recursiveLoop() {
//Do Stuff
this.timer = setTimeout(this.recursiveLoop.bind(this), rerun_time);
}
But sometimes this loop gets stuck and I want it to automatically notice it, clean up and restart. So I tried doing something like this:
this.timer = null;
async recursiveLoop() {
this.long_timer = setTimeout(() => throw new Error('Taking too long!'), tooLong);
//Do Stuff
this.timer = setTimeout(this.recursiveLoop.bind(this), rerun_time);
}
main() {
//Do other asynchronous stuff
recursiveLoop()
.then()
.catch((e) => {
console.log(e.message);
cleanUp();
recursiveLoop();
}
}
I can't quite debug where it gets stuck, because it seems quite random and the program runs on a virtual machine. I still couldn't reproduce it locally.
This makeshift solution, instead of working, keeps crashing the whole node.js aplication, and now I am the one stuck. I have the constraint of working with node.js 14, without using microservices, and I never used child process before. I am a complete beginner. Please help me!

If you have a black box of code (which is all you've given us) with no way to detect errors on it and you just want to know when it is no longer generating results, you can put it in a child_process and ask the code in the child process to send you a message every time it runs an iteration. Then, in your main process, you can set a timer that resets itself every time it gets one of these "health" messages from the child. If the timer fires without getting a health message, then the child must be "stuck" because you haven't heard from it within your timeout time. You can then kill the child process at that point and restart it.
But, that is a giant hack. You should FIX the code that gets stuck or at least understand what's going on. Probably you're either leaking memory, file handles, database handles, running code that uses locks and messes up or there are unhandled errors happening. All are indications of code that should be fixed.

Cloud Functions continuously executing after timeout

I have a firestore app with a cloud function that triggers off a cronjob.
The cloud function takes a long time and pulls a large amount of data. I've set the memory limit of my function to 2Gb and the timeout to 540 second and Retry on failure is NOT checked.
The cloud function essentially looks like this:
export const fetchEpisodesCronJob = pubsub
.topic('daily-tick')
.onPublish(() => {
console.log(`TIMING - Before Fetches ${rssFeeds.length} feeds`, new Date())
return Promise.map(
rssFeeds.map(rssFeed => rssFeed.url),
url => fetch(url).catch(e => e).then(addFeedToDB), // <-- This can take a long time
{
concurrency: 4
}
).catch(e => {
console.warn('Error fetching feeds', e);
})
})
What I see in the logs however is this (Continues indefinitely):
As you can see the function is being finished with a status timeout however it's starting right back up again. What's weird is I've specified a 540 second limit however the timeout comes in at a consistent 5 minute mark. Also note I checked the cloud console and I manually spun off the last cronjob pubsub at 10:00AM yet you can see multiple pubsub triggers since then. (So I believe the cronjob is setup fine)
Also I get consistent errors repeating in the console:
My question is how do I prevent the cloud function from re-executing when it's already been killed due to a timeout. Is this a bug or do I need to explicitly set a kill statement somewhere.
Thanks!

So this is a bug with firebase. According to #MichaelBleigh
Turns out there's a backend bug in Cloud Functions that happens when a function is created with the default timeout but later increased that is causing this. A fix is being worked on and will hopefully address the issue soon.
If you're reading this in between now and when the bug is fixed though I found that the function will be triggered again ever 300 seconds. So an immediate work around for me is to set the timeout for 250 seconds and keep the time complexity of the function as minimal as possible. This may mean increasing the memory usage for the time being.

Is there any way to cleanly cancel asynchronous 'prompt' while it is waiting for input?

I'm working -- as an exercise -- on a Javascript game that involves a sequence of questions. I'm simply running it in Node, outputting to the console at the moment. I handle user input using the prompt package (https://www.npmjs.com/package/prompt).
All works fine except I also need to set a timeout on the length of time it takes to answer the question, and if the user exceeds that time, then move on to the next question. However at that point I am in the middle of prompt waiting for a response, and when I simply move on I start getting odd side effects, like typed input on the next round doubling up (and then on the next timeout tripling up) -- i.e. an s typed in yields sson the console.
Is there anyway with this package to cancel a prompt that is waiting for input? I looked through the documentation and didn't see a way. If not, do you know of a package that might provide this capability -- I looked and so far haven't found one.
I don't know if code helps, as the issue seems to be with the package itself, but here is what I'm doing:
A call for user input:
this.getUserName = function (callback) {
var schema = {
properties: {
name: {
description: "Tu nombre por favor:",
pattern: /^[áÁóÓíÍéÉñÑa-zA-Z\s\-]+$/,
message: 'Solo letras, por favor',
required: true
}
}
};
prompt.get(schema, callback);
};
when I call this I set up a timer using setTimeout
this.timer = setTimeout(this.timedOut.bind(this), this.ROUND_TIME);
this.prompter.getUserResponse(this.checkAnswer.bind(this));
when the timer times out I simply go on to a different piece of code, doing nothing to the prompt (which is still waiting), as I don't know how to "cancel" it…

I couldn't find a way to make it work with the NPM prompt package, but the package prompt-improved seems to have a timeout capability, although it's not well-documented.

data in local storage does not persist after closing and reoping app

I am using local storage to hold just one number (best score) in my game and it works just fine when playing the game..I can play multiple rounds and it correctly shows the top score but as soon as I close totally close the app and reopen, the best score is gone.
Controller:
$scope.$on("$ionicView.beforeEnter", function () {
if(window.localStorage.getItem("topscore")<$rootScope.totalscore){
window.localStorage.setItem("topscore", $rootScope.totalscore);
window.localStorage.setItem("password", "yessir");
$scope.bestscore=window.localStorage.getItem("topscore");
}
});
HTML:
BESTSCORE: {{bestscore}}
Using ionic framework and testing on actual iphone 6 device. Thanks for the help

If that function is called when your application starts up then you probably don't yet have totalScore value on your root scope. Nonetheless you seem to go ahead and set that value into local storage under the "topscore" key.
Basically, you are writing over the key whenever the application starts.

This bit should probably be outside the if clause so that the value is always loaded when your thing starts up. I also added a type conversion because localStorage only deals in strings, and a default value in case it's not set.
$scope.bestscore = parseInt(localStorage.getItem("topscore") || "0", 10);

CreateJS' PreloadJS progress event inaccurate

I'm trying to load some assets using the PreloadJS class from the CreateJS suite, but when very first progress event fired reports e.loaded and e.progress as 0.83, the numbers then decrease over the next few event before finally going back up again.
t.assets = new createjs.LoadQueue();
t.assets.installPlugin(createjs.Sound);
t.assets.setMaxConnections(10);
t.assets.addEventListener("progress", function(e){
console.log(e.loaded);
});
t.assets.addEventListener("complete", function(){
callback();
});
t.assets.loadManifest([
{ id: 'facebook_btn', src: 'img/ingame/facebook_white_btn.png' },
{ id: 'twitter_btn', src: 'img/ingame/twitter_white_btn.png' },
{ id: 'embed_btn', src: 'img/ingame/embed_white_btn.png' },
]);
I get these results in the console
0.8333333333333334
0.7142857142857143
0.625
0.5555555555555556
0.5
0.45454545454545453
0.4984983736293216
0.5894074645384125
0.6363636363636364
0.6663361591119469
0.7572452500210378
0.8261679748749072
0.9170770657839982
0.9390634318392196
1
Is this because it's working through the manifest initally and doesn't take into account everything right away?
Is checking the the progress is going the correct way before displaying these results in a preloader a good method of making sure it's sorted itself out?

Essentially the manifest is just providing a convienient way to deal with a batch of assets without you having to loop through them yourself. Have a look at the code, it's almost the same as the loadFile method, but loops through the array of objects. So it's not doing anything fancy in terms of better calculating the progress.
http://createjs.com/Docs/PreloadJS/files/.._src_preloadjs_LoadQueue.js.html#l898
You have a couple options though to make it look more accurate.
If you're not loading much and it's only going to take a few seconds you might just want to not use the progress event. Instead you can just catch load errors or other hangups.
If you are loading lots of things and it could take some time then consider waiting a few seconds before displaying the progress. That gives the manifest time to add enough stuff that it should just be moving in a positive direction towards 1.