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# Auto detect text files and perform LF normalization | ||
* text=auto | ||
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# Custom for Visual Studio | ||
*.cs diff=csharp | ||
*.sln merge=union | ||
*.csproj merge=union | ||
*.vbproj merge=union | ||
*.fsproj merge=union | ||
*.dbproj merge=union | ||
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# Standard to msysgit | ||
*.doc diff=astextplain | ||
*.DOC diff=astextplain | ||
*.docx diff=astextplain | ||
*.DOCX diff=astextplain | ||
*.dot diff=astextplain | ||
*.DOT diff=astextplain | ||
*.pdf diff=astextplain | ||
*.PDF diff=astextplain | ||
*.rtf diff=astextplain | ||
*.RTF diff=astextplain |
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/_site | ||
/*.lock |
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www.quartz-scheduler.net |
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--- | ||
layout: default | ||
title: Frequently Asked Questions | ||
--- | ||
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*This FAQ was adapted from Quartz Java* | ||
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# General Questions | ||
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## What is Quartz | ||
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Quartz is a job scheduling system that can be integrated with, or used along | ||
side virtually any other software system. The term "job scheduler" seems to | ||
conjure different ideas for different people. As you read this tutorial, you | ||
should be able to get a firm idea of what we mean when we use this term, but | ||
in short, a job scheduler is a system that is responsible for executing | ||
(or notifying) other software components when a pre-determined (scheduled) | ||
time arrives. | ||
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Quartz is quite flexible, and contains multiple usage paradigms that can be | ||
used separately or together, in order to achieve your desired behavior, and | ||
enable you to write your code in the manner that seems most 'natural' to | ||
your project. | ||
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Quartz is very light-weight, and requires very little setup/configuration - | ||
it can actually be used 'out-of-the-box' if your needs are relatively basic. | ||
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Quartz is fault-tolerant, and can persist ('remember') your scheduled | ||
jobs between system restarts. | ||
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Although Quartz is extremely useful for simply running certain system | ||
processes on given schedules, the full potential of Quartz can be realized | ||
when you learn how to use it to drive the flow of your application's | ||
business processes. | ||
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## What is Quartz - From a Software Component View? | ||
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Quartz is distributed as a small dynamically linked library (.dll file) | ||
that contains all of the core Quartz functionality. The main interface (API) to this | ||
functionality is the Scheduler interface. It provides simple operations | ||
such as scheduling/unscheduling jobs, starting/stopping/pausing the scheduler. | ||
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If you wish to schedule your own software components for execution they must | ||
implement the simple Job interface, which contains the method execute(). | ||
If you wish to have components notified when a scheduled fire-time arrives, | ||
then the components should implement either the TriggerListener or JobListener | ||
interface. | ||
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The main Quartz 'process' can be started and ran within your own application, | ||
or a stand-alone application (with an remote interface). | ||
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# Why not just use System.Timers.Timer? | ||
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.NET Framework has "built-in" timer capabilities, through the | ||
System.Timers.Timer class - why would someone use Quartz rather than these | ||
standard features? | ||
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There are many reasons! Here are a few: | ||
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* Timers have no persistence mechanism. | ||
* Timers have inflexible scheduling (only able to set start-time & repeat interval, nothing based on dates, time of day, etc. | ||
* Timers don't utilize a thread-pool (one thread per timer) | ||
* Timers have no real management schemes - you'd have to write your own mechanism for being able to remember, organize and retreive your tasks by name, etc. | ||
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...of course to some simple applications these features may not be important, | ||
in which case it may then be the right decision not to use Quartz.NET. | ||
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## How do I build the Quartz source? | ||
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Although Quartz ships "pre-built" many people like to make their own | ||
alterations and/or build the latest 'non-released' version of Quartz from | ||
Subversion. To do this, follow the instructions in the "README.TXT" file | ||
that ships with Quartz. | ||
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# Miscellaneous Questions</title> | ||
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## How many jobs is Quartz capable of running? | ||
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This is a tough question to answer... the answer is basically "it depends". | ||
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I know you hate that answer, to here's some information about what it depends "on". | ||
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First off, the JobStore that you use plays a significant factor. | ||
The RAM-based JobStore is MUCH (1000x) faster than the ADO.NET-based JobStore. | ||
The speed of AdoJobStore depends almost entirely on the speed of the | ||
connection to your database, which data base system that you use, and what | ||
hardware the database is running on. Quartz actually does very little | ||
processing itself, nearly all of the time is spent in the database. Of course | ||
RAMJobStore has a more finite limit on how many Jobs & Triggers can be stored, | ||
as you're sure to have less RAM than hard-drive space for a database. | ||
You may also look at the FAQ "How do I improve the performance of AdoJobStore?" | ||
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So, the limitting factor of the number of Triggers and Jobs Quartz can "store" | ||
and monitor is really the amount of storage space available to the JobStore | ||
(either the amount of RAM or the amount of disk space). | ||
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Now, aside from "how many can I store?" is the question of "how many jobs | ||
can Quartz be running at the same moment in time?" | ||
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One thing that CAN slow down quartz itself is using a lot of listeners | ||
(TriggerListeners, JobListeners, and SchedulerListeners). The time spent in | ||
each listener obviously adds into the time spent "processing" a job's | ||
execution, outside of actual execution of the job. This doesn't mean that | ||
you should be terrified of using listeners, it just means that you should | ||
use them judiciously - don't create a bunch of "global" listeners if you can | ||
really make more specialized ones. Also don't do "expensive" things in the | ||
listeners, unless you really need to. Also be mindful that many | ||
plug-ins (such as the "history" plugin) are actually listeners. | ||
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The actual number of jobs that can be running at any moment in time is | ||
limitted by the size of the thread pool. If there are five threads in | ||
the pool, no more than five jobs can run at a time. Be careful of making a | ||
lot of threads though, as the VM, Operating System, and CPU all have a hard | ||
time juggling lots of threads, and performance degrades just because of all | ||
of the management. In most cases performance starts to tank as you get into | ||
the hundreds of threads. Be mindful that if you're running within an | ||
application server, it probably has created at least a few dozen threads | ||
of its own! | ||
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Aside from those factors, it really comes down to what your jobs DO. | ||
If your jobs take a long time to complete their work, and/or their work is | ||
very CPU-intensive, then you're obviously not going to be able to run very | ||
many jobs at once, nor very many in a given spanse of time. | ||
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Finally, if you just can't get enough horse-power out of one Quartz instance, | ||
you can always load-balance many Quartz instances (on separate machines). | ||
Each will run the jobs out of the shared database on a first-come first-serve | ||
basis, as quickly as the triggers need fired. | ||
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So here you are this far into the answer of "how many", and I still | ||
haven't given you a number And I really hate to, because of all of the | ||
variables mentioned above. So let me just say, there are installments of | ||
Quartz Java out there that are managing hundreds-of-thousands of Jobs and Triggers, | ||
and that at any given moment in time are executing dozens of jobs - and this | ||
excludes using load-balancing. With this in mind, most people should feel | ||
confident that they can get the performance out of Quartz that they need. | ||
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# Questions About Jobs | ||
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## How can I control the instantiation of Jobs?</title> | ||
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See Quartz.Spi.IJobFactory and the Quartz.IScheduler.JobFactory property. | ||
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## How do I keep a Job from being removed after it completes?</title> | ||
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Set the property JobDetail.Durable = true - which instructs Quartz not to | ||
delete the Job when it becomes an "orphan" (when the Job not longer has a | ||
Trigger referencing it). | ||
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## How do I keep a Job from firing concurrently? | ||
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Make the job class implement IStatefulJob rather than Job. Read the API | ||
documentation for IStatefulJob for more information. | ||
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## How do I stop a Job that is currently executing? | ||
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See the Quartz.IInterruptableJob interface, and the | ||
Scheduler.Interrupt(string, string) method. | ||
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# Questions About Triggers | ||
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## How do I chain Job execution? Or, how do I create a workflow? | ||
There currently is no "direct" or "free" way to chain triggers with Quartz. | ||
However there are several ways you can accomplish it without much effort. | ||
Below is an outline of a couple approaches: | ||
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One way is to use a listener (i.e. a TriggerListener, JobListener or | ||
SchedulerListener) that can notice the completion of a job/trigger and then | ||
immediately schedule a new trigger to fire. This approach can get a bit | ||
involved, since you'll have to inform the listener which job follows which | ||
- and you may need to worry about persistence of this information. | ||
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Another way is to build a Job that contains within its JobDataMap the name | ||
of the next job to fire, and as the job completes (the last step in its | ||
Execute() method) have the job schedule the next job. Several people are | ||
doing this and have had good luck. Most have made a base (abstract) class | ||
that is a Job that knows how to get the job name and group out of the | ||
JobDataMap using special keys (constants) and contains code to schedule the | ||
identified job. Then they simply make extensions of this class that included | ||
the additional work the job should do. | ||
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In the future, Quartz will provide a much cleaner way to do this, but until | ||
then, you'll have to use one of the above approaches, or think of yet another | ||
that works better for you. | ||
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## Why isn't my trigger firing? | ||
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The most common reason for this is not having called Scheduler.Start(), | ||
which tells the scheduler to start firing triggers. | ||
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The second most common reason is that the trigger or trigger group | ||
has been paused. | ||
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## Daylight Saving Time and Triggers | ||
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CronTrigger and SimpleTrigger each handle daylight savings time in their own | ||
way - each in the way that is intuitive to the trigger type. | ||
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First, as a review of what daylight savings time is, please read this resource: | ||
http://webexhibits.org/daylightsaving/g.html . Some readers may be unaware | ||
that the rules are different for different nations/contents. For example, | ||
the 2005 daylight savings time starts in the United States on April 3, but | ||
in Egypt on April 29. It is also important to know that not only the dates | ||
are different for different locals, but the time of the shift is different | ||
as well. Many places shift at 2:00 am, but others shift time at 1:00 am, | ||
others at 3:00 am, and still others right at midnight. | ||
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SimpleTrigger allows you to schedule jobs to fire every N milliseconds. | ||
As such, it has to do nothing in particular with respect to daylight | ||
savings time in order to "stay on schedule" - it simply keeps firing every | ||
N milliseconds. Regardless your SimpleTrigger is firing every 10 seconds, | ||
or every 15 minutes, or every hour or every 24 hours it will continue to do | ||
so. However the implication of this which confuses some users is that if | ||
your SimpleTrigger is firing say every 12 hours, before daylight savings | ||
switches it may be firing at what appears to be 3:00 am and 3:00 pm, | ||
but after daylight savings 4:00 am and 4:00 pm. This is not a bug | ||
- the trigger has kept firing exacly every N milliseconds, it just that the | ||
"name" of that time that humans impose on that moment has changed. | ||
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CronTrigger allows you to schedule jobs to fire at certain moments with | ||
respect to a "gregorian calendar". Hence, if you create a trigger to fire | ||
every day at 10:00 am, before and after daylight savings time switches it | ||
will continue to do so. However, depending on whether it was the Spring or | ||
Autumn daylight savings event, for that particular Sunday, the actual time | ||
interval between the firing of the trigger on Sundary morning at 10:00 am | ||
since its firing on Saturday morning at 10:00 am will not be 24 hours, | ||
but will instead be 23 or 25 hours respectively. | ||
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There is one additional point users must understand about CronTrigger with | ||
respect to daylight savings. This is that you should take careful thought | ||
about creating schedules that fire between midnight and 3:00 am (the critical | ||
window of time depends on your trigger's locale, as explained above). | ||
The reason is that depending on your trigger's schedule, and the particular | ||
daylight event, the trigger may be skipped or may appear to not fire for an | ||
hour or two. As examples, say you are in the United States, where daylight | ||
savings events occur at 2:00 am. If you have a CronTrrigger that fires every | ||
day at 2:15 am, then on the day of the beginning of daylight savings time | ||
the trigger will be skipped, since, 2:15 am never occurs that day. If you | ||
have a CronTrigger that fires every 15 minutes of every hour of every day, | ||
then on the day daylight savings time ends you will have an hour of time | ||
for which no triggerings occur, because when 2:00 am arrives, it will become | ||
1:00 am again, however all of the firings during the one o'clock hour have | ||
already occurred, and the trigger's next fire time was set to 2:00 am | ||
- hence for the next hour no triggerings will occur. | ||
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In summary, all of this makes perfect sense, and should be easy to remember | ||
if you keep these two rules in mind: | ||
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* SimpleTrigger ALWAYS fires exacly every N seconds, with no relation to the time of day. | ||
* CronTrigger ALWAYS fires at a given time of day and then computes its next time to fire. If that time does not occur on a given day, the trigger will be skipped. If the time occurs twice in a given day, it only fires once, because after firing on that time the first time, it computes the next time of day to fire on. | ||
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# Questions About AdoJobStore | ||
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## How do I improve the performance of AdoJobStore? | ||
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There are a few known ways to speed up AdoJobStore, only one of which is | ||
very practical. | ||
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First, the obvious, but not-so-practical: | ||
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* Buy a better (faster) network between the machine that runs Quartz, and the machine that runs your RDBMS. | ||
* Buy a better (more powerful) machine to run your database on. | ||
* Buy a better RDBMS. | ||
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Use driver delegate implementation that is specific to your database, like SQLServerDelegate, for best performance. | ||
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Now for something simple, but effective: Build indexes on the Quartz tables. | ||
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Most database systems will automatically put indexes on the primary-key | ||
fields, many will also automatically do it for the foreign-key field. | ||
Make sure yours does this, or make the indexes on all key fields | ||
of every table manually. | ||
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Next, manually add some additional indexes: most important to index are | ||
the TRIGGER table's "next_fire_time" and "state" fields. Last | ||
(but not as important), add indexes to every column on the FIRED_TRIGGERS table. | ||
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**Create Table Indexes** | ||
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```sql | ||
create index idx_qrtz_t_next_fire_time on qrtz_triggers(NEXT_FIRE_TIME); | ||
create index idx_qrtz_t_state on qrtz_triggers(TRIGGER_STATE); | ||
create index idx_qrtz_t_nf_st on qrtz_triggers(TRIGGER_STATE,NEXT_FIRE_TIME); | ||
create index idx_qrtz_ft_trig_name on qrtz_fired_triggers(TRIGGER_NAME); | ||
create index idx_qrtz_ft_trig_group on qrtz_fired_triggers(TRIGGER_GROUP); | ||
create index idx_qrtz_ft_trig_name on qrtz_fired_triggers(TRIGGER_NAME); | ||
create index idx_qrtz_ft_trig_n_g on qrtz_fired_triggers(TRIGGER_NAME,TRIGGER_GROUP); | ||
create index idx_qrtz_ft_trig_inst_name on qrtz_fired_triggers(INSTANCE_NAME); | ||
create index idx_qrtz_ft_job_name on qrtz_fired_triggers(JOB_NAME); | ||
create index idx_qrtz_ft_job_group on qrtz_fired_triggers(JOB_GROUP); | ||
``` |
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source 'https://rubygems.org' | ||
gem 'github-pages' |
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# Name of your blog (this will show up at the top of your page and in the RSS feed) | ||
name: Quartz.NET Documentation | ||
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# Short description (goes below the title; it will also be used in the RSS feed) | ||
description: | ||
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# Your name, as you want it to appear underneath each post and in the footer | ||
author: Marko Lahma | ||
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category_dir: / | ||
baseurl: | ||
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url: http://www.quartz-scheduler.net/ | ||
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#### Under the Hood Stuff ##### | ||
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markdown: redcarpet | ||
pygments: true | ||
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exclude: [README.markdown, package.json, grunt.js, Gruntfile.js, node_modules, Gemfile, Gemfile.lock] | ||
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encoding: UTF-8 |
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