I am currently working on a project that runs online tournaments. Normally admins of the site will generate brackets when it is time for the tournaments to start, but we have run into inconsistent start times, etc. and i am looking into proper ways to automate this process.
I have looked into running cronjobs every x min to check if a bracket needs to be generated but i am worried about issue when it comes to overlapping cronjobs, having to create/manage cronjobs through cpanel etc.
I was thinking about other solutions and thought it would be great if a user could load a page, the backend checks timestamps and determines if the bracket should be generated. An event is then fired/set to begin the auto-generation process elsewhere so it does not impact user load times. I just do not know the best route of going about this.
PS: I just need an idea of the direction i should be looking into so i can learn how to solve this issue i am not looking to copy and paste code. I just haven't been able to find anything. All of my search results provide cronjob examples.
EDIT
After thinking about things could using this work?
$(document).ready(function() {
$.ajax('Full Url Path Here');
})
I don't need to pass user input, or return any data i simply need a way to fire an event, it would be easy to include this only when needed via a helper class. Also i won't necessarily have to worry about users attempting to access i can restrict the route to ajax only requests and since nothing is needed/used on input or returned as output what can happen?
You could do it everytime a user loads a page (idea not tested, but theoretically possible):
1) Create a file and store the timestamp of the last time you updated the database.
2) Everytime a user loads a page, read that timestamp and check if 15 minutes passed.
3) If 15 minutes passed: Run a background script (with shell_exec?) that will do what you want and update the timestamp when it's done executing.
One obvious flaw with this system is that if you have no visitors in let's say a 30 minute frame, you will miss 2 updates. Though I guess that if you have no visitors you also have no point in generating brackets?
Related
I've been looking through Laravel's queue and schedulers and I'm not sure if it's what I need to do what I want. I'll try explain simply.
First, I hit a submit (basic form) that creates a db row with say a number and a created_at and finished_at. JS then creates a timer on the page that counts down (math) from the created at to the finished time.
I can do all that fine, what I'm struggling to get my head around is how do I make this then change that number value of 0 to 1 say after 10 minutes, or whatever time I wanted to specify? I'm not sure how to go about this. This sort of stuff is new to me.
Any help/pointing me in the right direction would be great! Explanations too. :)
Edit: To add, I looked at things like socket.io but I'm not sure if that's what I want too and if I can even use that with laravel as it's a framework off of node.js
Is the backend actually doing any work besides storage? If not I would skip the complexity of trying to open a web socket to tell the frontend the task is finished.
If all you're trying to accomplish is display something on the frontend to the user after an interval of time I would just use JS 100%.
However if the backend does need to do work and trigger the display change on the frontend you will need to open up a web socket.
Your constraint on Laravel's scheduling is that they are run at predefined times. So if these actions are triggered by the user and not a set time, skip using the scheduler. Instead use Events to broadcast something to node.
I'm working on a basic lamp(willing to change) website , and I currently need a way to run some function on the server that runs for several hours per user, and every X hours it needs to query the mysql database to see if the value for that user has been updated, if it hasn't it need it to insert a new record in the database...I also should mention that the 'every X hours' can change per user too, and the total runtime of the function per user can also vary.
So basically I need a function that runs continuously on the server for few hours per user. What is the best way to do this? I want the site to be able to support many users (like 10000 +).
I'm willing to try new technologies for every aspect of the site, I'm still in the design phase and I was looking for some input.
I've looked at cron but not really sure how well it would work when dealing with so many users...
edit: Here is a typical scenario of events;
User presses button on the website and closes the browser.
Server starts a timer from when they pressed the button, now
the server will check if that user has pressed a different button within a given time frame (time frame can change per user), say within 30 minutes. If they didn't press the other button then the server needs to automatically insert a new record in the database.
The script will need to continue running, checking every 30 mins for say the next 5 hours.
Thank you!
Cron would work as well as you can code the page it will run. It's not a cron limitation.
The question is ambiguous btw. Maybe explaining your full scenario would help.
Meanwhile, my suggestion would be to set up a scrip that allows you to manually check what you need to check.
You definitely need the DB to be InnoDB optimized with proper indexes to be able to support 1000 plus users.
To alleviate the number of calls to the database, a common practice is to run scripts only on what you are interested (so in the case of users you would only select those who have logged on in say the past 3 hours)
That's achievable in 2 ways, a simple select statement, or by adding entries to a specific table on the login page, and remove them after the automated script has finished running.
All of this is pure theory without understanding exactly what you need to do though.
You are telling what/how you want to do, but not why you want to do it. Maybe letting us know why could lead to a different how ;)
However, what you can do is still use cron (or anything similar). The trick is to have
a last_interaction timestamp column
a maximum_interval column
a daily_runtime column
in your users database. Not optimized but you are in the design phase so you shouldn't pay too much attention to the performance aspect (except is explicitly required).
Ok I know the title doesn't really tell you what my problem is but I'll try it now.
I am developing a game. People can subscribe their animals for a race. That race starts at a specific time. It is a race for which ALL users can subscribe. So the calculation of which animal is first, second etc. happens in an php file that is executed, every 2mins there is a new calculation for about 1h. So there are 30 calculations. But ofc. this code is not connected to the logged in user. The logged in user can click on the LIVE button to see the current result.
Example: There is a race at 17.00 later today. 15 animals subscribed, from 4 players and they can all check how their animals are doing.
I do not want someone to post me the full code but I want to know how I should let a php code run for about 1 hour (so execute code, sleep 2min, new calculation, sleep 2min and so on) on my server or so. So it is not connected to the user.
I thought about cron jobs but that is really not the solution for this I believe.
Thank you for reading :p
Two approaches:
You use an algorithm which will always come to the same conclusion, regardless of when it is run and who runs it. You just define the starting parameters, then at any time you can calculate the result (or the intermediate result at any point in time between start and finish) when needed. So any user can at any time visit your site and the algorithm will calculate the current standings on the fly from some fixed starting condition.
Alternatively, you keep all data in a central data store and actually update the data in certain intervals; any user can request the current standings at any time and the latest data from the datastore will be used. You will still need an algorithm that has traits of the one described above, since you're likely explicitly not actually running the simulation in real time. Just every x seconds, you run your calculations again, calculating what is supposed to have changed from the last time you ran them.
In essence, any algorithm you use needs this approach. Even a "realtime" program simply keeps looping, changing values little by little from their previous state. The interval between theses changes can be arbitrarily stretched out, to the point where you calculate nothing until it becomes necessary. In the meantime, you just store all the data you need in a database.
Cron jobs are the wright way i think. Check this out when you are not so good with algorithm:How To: PHP with Cron job Maybe you have to use different cron jobs.
I've decided to create a web based chat system for the experience. I'm using a mixture of AJAX(jQuery), PHP, and JSON to transfer the data. Now that I've started thinking about certain things, I've come to a mind block.
Right now, I use javascript to post the last loaded message id to a php file that queries the data and echoes new posts in json and then displays those posts in order on the page. However, the dates don't reflect the current time for the user. Since I use php to get the current time, I have no idea how to display the correct time to the user which takes into account of their time zone. Second, how would I incorporate a who's online list with this method? I could create a separate table and update it when a user creates a session and delete their name when they end the session; but what if they don't close it properly? Should I just add their last sent message into the the table and if it's been about 5 minutes since their last message consider the user disconnected? Lastly, is the method I'm using to collect new posts efficient? This there a better way to go about this? I appreciate any input.
This seems related: Determine a User's Timezone
I'm going to make you go there for the code snip so you give proper credit with your upvotes.
I get the impression that Javascript is the best/easiest way to get that data.
What I would probably do is use GMT or some other fixed time zone for all your server stuff and then just adjust that with js once it hits the browser depending on their time zone. Either that or just collect it once at the start of the conversation and adjust your output accordingly. There might be advantages to either way.
Edit:
Oh yeah, about the "who's online" I think you're headed in the right direction. I might suggest 2 lists. "Who's active" and "Who was active recently"
That way you can put people inactive after 5 mins and consider them disconnected after 10 or something. I guess it's about the same but it seems more accurate to me somehow.
The other option would be to set an ajax request to automatically fire of a request every minute or so. When they stop then you know the user is gone.
Bit of an odd question but I'm hoping someone can point me in the right direction. Basically I have two scenarios and I'd like to know which one is the best for my situation (a user checking a scoreboard on a high traffic site).
Top 10 is regenerated every time a user hits the page - increase in load on the server, especially in high traffic, user will see his/her correct standing asap.
Top 10 is regenerated at a set interval e.g. every 10 minutes. - only generates one set of results causing one spike every 10 minutes rather than potentially once every x seconds, if a user hits in between the refresh they won't see their updated score.
Each one has it's pros and cons, in your experience which one would be best to use or are there any magical alternatives?
EDIT - An update, after taking on board what everyone has said I've decided to rebuild this part of the application. Rather than dealing with the individual scores I'm dealing with the totals, this is then saved out to a separate table which sort of acts like a cached data source.
Thank you all for the great input.
Adding to Marcel's answer, I would suggest only updating the scoreboards upon write events (like new score or deleted score). This way you can keep static answers for popular queries like Top 10, etc. Use something like MemCache to keep data cached up for requests, or if you don't/can't install something like MemCache on your server serialize common requests and write them to flat files, and then delete/update them upon write events. Have your code look for the cached result (or file) first, and then iff it's missing, do the query and create the data
Nothing is never needed real time when it comes to the web. I would go with option 2 users will not notice that there score is not changing. You can use some JS to refresh the top 10 every time the cache has cleared
To add to Jordan's suggestion: I'd put the scorecards in a separate (HTML formatted) file, that is produced every time when new data arrives and only then. You can include this file in the PHP page containing the scorecard or even let a visitor's browser fetch it periodically using XMLHttpRequests (to save bandwidth). Users with JavaScript disabled or using a browser that doesn't support XMLHttpRequests (rare these days, but possible) will just see a static page.
The Drupal voting module will handle this for you, giving you an option of when to recalculate. If you're implementing it yourself, then caching the top 10 somewhere is a good idea - you can either regenerate it at regular intervals or you can invalidate the cache at certain points. You'd need to look at how often people are voting, how often that will cause the top 10 to change, how often the top 10 page is being viewed and the performance hit that regenerating it involves.
If you're not set on Drupal/MySQL then CouchDB would be useful here. You can create a view which calculates the top 10 data and it'll be cached until something happens which causes a recalculation to be necessary. You can also put in an http caching proxy inline to cache results for a set number of minutes.