is there any other option other than cron to schedule the running of a php backup script at a certain time?. I know you can use php itself to schedule things, but it will only fire if the site is getting traffic.
Are there any other options ?.
Thanks :-)
If you're talking about a database backup, then MySQL 5.1 and above has CREATE EVENT which can be used to trigger events (such as stored procedures that can dump table structure/data to file) at regular intervals or set times
Well, cron jobs is a solution. But not necessary in most cases.
If your script is doing something off the site (like sending an email or something), it must be a cron-job.
But...
I made a textbased rpg-game once where several actions were stored in the database waiting to get triggered at a specified time. I found out that it did not make any difference if the script fired at the time it should, or when the first person visiting the page after the time is beyond the timestamp. You could do these events before displaying the content of the page. (I used a file called monitor, to keep it simple).
Would you like to say more about your "event"?
Unless you feel like writing a daemon/service/etc., cron would be your best bet. If you need a job ran more often than minutely, use a lockfile solution and a looping script.
Well not really, Crons are your best bet.
Other than that call a script, and if certain parameters are met such as time elapsed then run the script.
Related
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
I need to show some basic stats on the front page of our site like the number of blogs, members, and some counts - all of which are basic queries.
Id prefer to find a method to run these queries say every 30 mins and store the output but im not sure of the best approach and I don't really want to use a cron. Basically, I don't want to make thousands of queries per day just to display these results.
Any ideas on the best method for this type of function?
Thanks in advance
Unfortunately, cron is better and reliable solution.
Cron is a time-based job scheduler in Unix-like computer operating systems. The name cron comes from the word "chronos", Greek for "time". Cron enables users to schedule jobs (commands or shell scripts) to run periodically at certain times or dates. It is commonly used to automate system maintenance or administration, though its general-purpose nature means that it can be used for other purposes, such as connecting to the Internet and downloading email.
If you are to store the output into disk file,
you can always check the filemtime is lesser than 30 minutes,
before proceed to re-run the expensive queries.
There is nothing at all wrong with using a cron to store this kind of stuff somewhere.
If you're looking for a bit more sophisticated caching methods, I suggest reading into memcached or APC, which could both provide a solution for your problem.
Cron Job is best approach nothing else i seen feasible.
You have many to do this, I think the good not the best, you can store your data on table and display it every 30 min. using the function sleep()
I recommend you to take a look at wordpress blog system, and specially at the plugin BuddyPress..
I did the same some time ago, and every time someone load the page, the query do the job and retrieve the information from database, I remenber It was something like
SELECT COUNT(*) FROM my_table
and I got the number of posts in my case.
Anyway, there are so many approach. Good Luck.
Dont forget The cron is always your best friend.
Using cron is the simplest way to solve the problem.
One good reason for not using cron - you'll be generating the stats even if nobody will request them.
Depending on the length of time it takes to generate the data (you might want to keep track of the previous counts and just add counts where the timestamp is greater than the previous run - with appropriate indexes!) then you could trigger this when a request comes in and the data looks as if it is stale.
Note that you should keep the stats in the database and think about how to implement a mutex to avoid multiple requests trying to update the cache at the same time.
However the right solution would be to update the stats every time a record is added. Unless you've got very large traffic volumes, the overhead would be minimal. While 'SELECT count(*) FROM some_table' will run very quickly you'll obviously run into problems if you don't simply want to count all the rows in a table (e.g. if blogs and replies are held in the same table). Indeed, if you were to implement the stats update as a trigger on the relevant tables, then you wouldn't need to make any changes to your PHP code.
I need a way to modify a value in a table after a certain amount of time has passed. My current method is as follow:
insert end time for wait period in table
when a user loads a page requesting the value to be changed, check to see if current >= end time
if it is, change the value and remove the end time field, if it isn't, do nothing
This is going to be a major feature on the site, and so efficiency is the key; with that in mind, you can probably see the problem with how I'm doing it. That same chunk of code is going to be called every time someone access a page that needs the information.
Any suggestions for improvements or better methods would be greatly appreciated, preferably in php or perl.
In response to cron job answers:
Thanks, and I'd like to do something like that if possible, but hosts limits are the problem. Since this is a major part of the app, it can't be limited.
why not use a cron to update this information behind the scenes? that way you offload the checks on each page hit, and can actually schedule the timing to meet your app's requirements.
Your solution sounds very logical, since you don't have access to cron. Another way could be storing the value in a file, and the next time the page is loaded check when it was last modified (filemtime("checkfile.txt")), and decide if it needs modifying again. You should test performance for both methods.
Can you use a cron job to check each field in the database periodically and update that way?
A big part of this is how frequently the updates are required. A lot of shared hosts limit the frequency of cron checks, for example no more than every 15 minutes, which could affect the application.
You could use a trigger of some sort on each page load. I really have no idea how that would affect performance but maybe somebody else can shed some light.
If performance really starts to be an issue, (which means a lot more than you probably realize) you could use memchached to store the info...