How can I set up a program in which a certain piece of data for a user is updated every hour. One example I can give is Mafia Wars. When you obtain property, your money is incremented every set amount of time based on which property it is. I'm not asking to spit out code for me, but rather to guide me in the right direction for a solution. I tried looking into cron jobs, but that only runs a script on a set time. Different users are going to be using this, and they may have different times to update their information. So thus, cron jobs are not applicable here.
You could still have cron jobs, just lots of them (not one per user, but maybe one per minute).
Also, Mafia Wars strikes me as not very interactive, so it may be enough to just update the data (after the fact) when the user (or some other part of the system) next looks at it. So when you log in after 37 hours, you get all the updates for the last 37 hours retroactively applied. Cheap trick, but if there is no need for a consistent global view, that might work, too.
A solution that I came up with when wondering how to implement such a thing is that whenever the player saves the game, the game saves the current time. Then, when the player loads the game back up, it calculates how many minutes have passed and figures out how much money the game should give the player. Then, you could update the SQL database to reflect the changes.
Why do you dismiss cron jobs? Have a cron job that runs a script in short intervals. Within this script, include logic to check which specific updates on the database have to be done.
A cron job that runs something is your friend.
What that something is, is up to you. It could be a PHP script that runs some mysql queries or procedures, or it could straight mysql command from the command line.
Either way, Cron (and other similiar tools) are exactly the bill for these tasks. It's lightweight, on nearly every server in the land, lots of help avaliable for it, and it 99.9999% of the time, it just works!
Related
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 search on the web and apparently there is no way to launch a php script without user interaction.
Few advisors recommend me Cron but I am not sure this is the right way to go.
I am building a website where auctions are possible just like ebay. And after an amount of time the objects are not available anymore and the auction is considered as finished.
I would like to know a way to interact with the database automatically.
When do you need to know if an object is available? -> Only if someone asks.
And then you have the user interaction you are searching for.
It's something different if you want to, let's say, send an email to the winner of an auction. In this case you'd need some timer set to the ending time of the auction. The easiest way to do this would be a cron job...
There are several ways to do this. Cron is a valid one of them and the one I would recommend if its available.
Another is to check before handling each request related to an object whether it is still valid. If it is not, you can delete it from the database on-the-fly (or do whatever you need to) and display a different page.
Also you could store the time at which your time-based script was run last in the database and compare that time with the current time. If the delay is large enough, you can run your time based code. However, this is prone to race conditions if multiple users hit the page at the same time, so the script may run multiple times (maybe this can be avoided using locks or anything though).
To edit cronjobs from the shell: crontab -e
A job to run every 10 minutes: */10 * * * * curl "http://example.com/finished.php"
TheGeekStuff.com cron Examples
Use heartbeat/bot implement
ation
Cron job that runs pretty frequently or a program that starts on boot and runs continuously (maybe sleeping periodically) is the way to go. With a cron job you'll need to make sure that you don't have two running at any given time or write it such that it doesn't matter if you have more than one working at any given time. With "resident" program you'll need to figure out how to handle the case when it crashes unexpectedly.
I wouldn't rely on this mechanism to actually close the auction, though. That should be handled in your database/web site. That is, the auction has a close time and either the database constraints or your code makes it impossible to bid on a closed auction. Notifying the winner and seller, setting up the payment process, etc. are things your service/scheduled task could do.
I need to develop a website that runs jobs at certain times (every 15 minutes) I'll use a cron to run the webpage.
What is the best way to store the jobs information in? Some jobs will be daily, others every 8 hours etc. To complicate matters, I also need to take into consideration the timezone differences. This shouldn't be too difficult as PHP has many timezone functions, but how do I integrate it in the programming of the next job to run?
Another question, is how will the user enter the information for the jobs to run? One option, similar to http://www.webcron.org, is to ask the user to select how often the jobs must run, but how do I store that info in a database?
Any assistance will be greatly appreciated!
I would use the crontab syntax, store it in a DB and run a separate crontab invoking the execution script every minute.
There are GPL classes that do that for you already, like : http://www.phpclasses.org/package/4140-PHP-Database-driven-PHP-job-scheduler-like-cron.html
Create a MySQL Event, that will take care also the storing, recurrence, execution.
I've heard about cron job and don't think the actual creation of it will be that hard to make but I've some concerns about how this will work with a large script.
Without going too much off-topic on my project i will stick with the basics about my situation. I need to make a script that every day performs a CURL fetch for data on a remote website and updates an database for each featured member on my website with it. In short, it's approximatively at this time 1000 times the script need to be executed but it will be a larger number as times goes by.
As you can guess, this will take a long time to preform so i'm worried about how the execution will work in a manner of not crashing in the middle of it.
My first thought was to perhaps split the users into groups and make the executions on a small amount of users each time but don't know how this is manageable ( will read on further about the topic when i got some form of confirmation on this).
So, to my question. Do you think there is any way for me to make this happen and do you perhaps have any suggestions on how to make this to work efficiently? All help i can get is appreciated. Thank you for your time.
bigger cron-jobs with php and mysql needs to be fragmented, since there is no way for you to 'nice' them, (reduce their os priority). Even if you nice the script, the mysql-requests will be executed without this concern.
From what you're describing there's two aspects to consider:
Congestion of network bandwith
Congestion of database throughput
I'd recommend a fragmented solution where you call your script from cron more often, and let the script execute only a small amount of the total job. The job should further be canceled (postponed to next run) if i/o-bandwith or cpu-usage is above any limit that may affect response-time to visitors.
regards,
/t
One Way:
I'm usually against putting logic in the database, but in this case a stored procedure might help. It will run your job faster (since it's a large one) and also you want to lock the tables as you do it. That way, if the script that calls the stored procedure gets hit by cron before the original job was over with it wont edit your database while the first one is running.
The actual time can i not give an
straight answer on but based on
previously experiences this will take
longer then the max execution time.
So solve that problem. There's a reason you can have a different php.ini for the command line interface. Then you can simply focus on processing all users in one script.
I solved this program using the files of cron job as differents cron jobs with small pieces. If you are using PHP you can set a cron job to domain/cronjob1.php, domain/cronjob2.php limiting the database lets say 10 with
$sql="SELECT * FROM table LIMIT 10";
to cronjob 1 and the rest in cronjo2