DotNetNuke Scheduler Explained
I have found that many people that work with DotNetNuke sites are often unfamiliar
with the various scheduled tasks that are implemented within DotNetNuke. Is
this a bad thing? It depends, by default the configuration of scheduled tasks
will work just fine, but as your site grows there are specific tasks that can become
problematic due to the size of the site, resulting in increased resources being
used or worse site failure/errors. This article will discuss each of the default
tasks that are included in DotNetNuke, I will describe the function of each and
discuss the default schedule and when you should change the schedule.
DotNetNuke.Entities.Users.PurgeUsersOnline
This task is one that is used by the Users Online module within DotNetNuke.
When this task executes it will remove users from the listing of online users that
are no longer active in your site. When using this module the time frequency
for this module is something that you want to take into careful consideration, more
details will be discussed in the "When to change" section
Standard Schedule
By default this task is NOT ENABLED by DotNetNuke, if you enable users online it
will execute every 1 minute to purge the users
When to Change
Typically the default values for this functionality is ok if you are using the module,
if you run an incredibly high activity site though you might consider adjusting
this to run every 5 minutes or so, just to reduce the minimal load that it does
add to your site
DotNetNuke.Services.Log.SiteLog.PurgeSiteLog
This task if it is enabled will purge the records in the site log that are older
than the specified history time. This task is highly important as when using
the site log this will prevent the log table from growing too large
Standard Schedule
By default this task is NOT ENABLED by DotNetNuke, if you enable this task the default
run frequency is once per day.
When to Change
This task is one that by the nature of how it works is best to leave at a 1 per
day schedule as it only cleans records based on a daily basis
DotNetNuke.Services.Scheduling.PurgeScheduleHistory
This task is used to purge records from the Schedule History table. This is
an important task because if your schedule history is left alone it is very possible
for your database size to grow in a very rapid manner due to the sheer number of
items that are completed by the scheduler.
Standard Schedule
By default this task is ENABLED by DotNetNuke and will execute once per day.
When to Change
This is another task that due to the nature of the action it performs changes to
the schedule are not needed
DotNetNuke.Services.Log.EventLog.PurgeLogBuffer
This task is used to purge records from the Event Log queue to the database.
This is an important feature of DotNetNuke as this task is what ensures that all
actions are successfully recorded to the EventLog table.
Standard Schedule
By default this task is ENABLED by DotNetNuke and will execute once per minute
When to Change
You can modify this task to run less frequently on a highly active site and it might
have minimal performance modifications. For example if it runs every minute
and takes 5 seconds, you could schedule it to run every 5 minutes and it would take
25 seconds. However, in my experience with DotNetNuke it is not ever necessary
to modify this task.
DotNetNuke.Services.Log.EventLog.SendLogNotifications
This task is responsible for sending e-mail notifications to the administrator from
the event log system.
Standard Schedule
By default this task is NOT ENABLED by DotnetNuke, if enabled it will execute once
every 5 minutes by default.
When to Change
Due to the nature of urgent updates to the administrator, if this task is enabled
I would not recommend changing the interval.
DotNetNuke.Services.Search.SearchEngineScheduler
This task is responsible for the population of the search engine within DotNetNuke.
When this task is executed all modules that support ISearchable will be polled for
index information and if any exists it will be added to the search index.
Standard Schedule
By default this task is ENABLED by DotNetNuke and will execute once every 30 minutes
When to Change
This task is typically the one that causes the most problems. Due to the nature
of the search engine and how it queries modules for information it can take an INCREDIBLY
long time for this code to run on large DNN sites (I have noticed times of over
15 hours for some clients). Therefore if you have a large site you might want
to change this for two reasons.
The first being the additional errors that will be thrown if the process runs for
more than 30 minutes. If the scheduler is still executing the index process
when it tries to start again a "cannot insert duplicate key" error will be encountered.
This adds to the number of entries in your event log and is an overall bad practice.
The second being the server resources that are being used. The search indexing
process is very database intensive and depending on your setup could cause noticable
performance reductions to your visitng clients. If you can get away with it
I would highly recommend having this run no more than once per 6-8 hours.
If you have a more active site you can leave it as is, however, keep an eye on your
event log for errors.
DotNetNuke.Modules.Admin.ResourceInstaller.InstallResources
This task is responsible for the automatic installation of modules that have been
placed in the various /Install folders in your DotNetNuke installation.
Standard Schedule
By default this task is NOT ENABLED by DotnetNuke, if enabled it will execute once
every 30 minutes by default.
When to Change
You can enable this task if you want to automatically install modules, however,
I personally recommend NOT using this feature
DotNetNuke.Services.FileSystem.SynchronizeFileSystem
This task is responsible for updating the File Manager by syncronizing the DNN file
system with your physical file system. This is needed if you add many files
to your site via FTP and not using one of the "DNN ways" of uploading
Standard Schedule
By default this task is NOT ENABLED by DotnetNuke, if enabled it will execute once
every hour by default.
When to Change
If you use FTP to upload files to your /Portals/<portalId> folder you might
enable this option, however, I personally recommend just using the "Recursive" sync
option within file manager whenever I have an issue. My reasons for this are
that if you have a large number of files, this task can take a very long time to
execute.
DotNetNuke.Services.Cache.PurgeCache
This scheduled task is responsible for purging cache files from the hard drive when
using the "Disk" method of caching. If you are using the "Disk" caching method
this is a key scheduled task.
Standard Schedule
By default this task is ENABLED by DotNetNuke and will execute once per 2 hours.
When to Change
You can disable this task if you are working with "Memory" caching (which I highly
recommend).
Disclaimer/Conclusion
This guide has been provided as a quick reference to explain some of the "default"
scheduled tasks that are available to you in DotNetNuke. It is your responsibility
to determine which tasks if any need to be modified from the default configuration.
Without a detailed look at the entire DNN solution it is impossible to provide a
blanket set of "rules" for setting scheduled tasks. If you have any specific
questions about this article please ask them below, if you need techical assistance
please visit my forum for assistance.
Posted by Mitchel on Wednesday, February 13, 2008
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