The scheduler component manages task scheduling within your PHP application, like running a task each night at 3 AM, every two weeks except for holidays or any other custom schedule you might need.
This component is useful to schedule tasks like maintenance (database cleanup, cache clearing, etc.), background processing (queue handling, data synchronization, etc.), periodic data updates, scheduled notifications (emails, alerts), and more.
This document focuses on using the Scheduler component in the context of a full stack Symfony application.
In applications using Symfony Flex <symfony-flex>, run this command to install the scheduler component:
$ composer require symfony/schedulerThe main benefit of using this component is that automation is managed by your application, which gives you a lot of flexibility that is not possible with cron jobs (e.g. dynamic schedules based on certain conditions).
At its core, the Scheduler component allows you to create a task (called a message) that is executed by a service and repeated on some schedule. It has some similarities with the Symfony Messenger </components/messenger> component (such as message, handler, bus, transport, etc.), but the main difference is that Messenger can't deal with repetitive tasks at regular intervals.
Consider the following example of an application that sends some reports to customers on a scheduled basis. First, create a Scheduler message that represents the task of creating a report:
// src/Scheduler/Message/SendDailySalesReports.php
namespace App\Scheduler\Message;
class SendDailySalesReports
{
public function __construct(private int $id) {}
public function getId(): int
{
return $this->id;
}
}Next, create the handler that processes that kind of message:
// src/Scheduler/Handler/SendDailySalesReportsHandler.php
namespace App\Scheduler\Handler;
use App\Scheduler\Message\SendDailySalesReports;
use Symfony\Component\Messenger\Attribute\AsMessageHandler;
#[AsMessageHandler]
class SendDailySalesReportsHandler
{
public function __invoke(SendDailySalesReports $message)
{
// ... do some work to send the report to the customers
}
}Instead of sending these messages immediately (as in the Messenger component), the goal is to create them based on a predefined frequency. This is possible thanks to Symfony\\Component\\Scheduler\\Messenger\\SchedulerTransport, a special transport for Scheduler messages.
The transport generates, autonomously, various messages according to the assigned frequencies. The following images illustrate the differences between the processing of messages in Messenger and Scheduler components:
In Messenger:
In Scheduler:
Another important difference is that messages in the Scheduler component are recurring. They are represented via the Symfony\\Component\\Scheduler\\RecurringMessage class.
The configuration of the message frequency is stored in a class that implements Symfony\\Component\\Scheduler\\ScheduleProviderInterface. This provider uses the method Symfony\\Component\\Scheduler\\ScheduleProviderInterface::getSchedule to return a schedule containing the different recurring messages.
The Symfony\\Component\\Scheduler\\Attribute\\AsSchedule attribute, which by default references the schedule named default, allows you to register on a particular schedule:
// src/Scheduler/SaleTaskProvider.php
namespace App\Scheduler;
use Symfony\Component\Scheduler\Attribute\AsSchedule;
use Symfony\Component\Scheduler\Schedule;
use Symfony\Component\Scheduler\ScheduleProviderInterface;
#[AsSchedule]
class SaleTaskProvider implements ScheduleProviderInterface
{
public function getSchedule(): Schedule
{
// ...
}
}Tip
By default, the schedule name is default and the transport name follows the syntax: scheduler_nameofyourschedule (e.g. scheduler_default).
Tip
Memoizing your schedule is a good practice to prevent unnecessary reconstruction if the getSchedule() method is checked by another service.
A RecurringMessage is a message associated with a trigger, which configures the frequency of the message. Symfony provides different types of triggers:
Symfony\\Component\\Scheduler\\Trigger\\CronExpressionTriggerA trigger that uses the same syntax as the cron command-line utility.
Symfony\\Component\\Scheduler\\Trigger\\CallbackTriggerA trigger that uses a callback to determine the next run date.
Symfony\\Component\\Scheduler\\Trigger\\ExcludeTimeTriggerA trigger that excludes certain times from a given trigger.
Symfony\\Component\\Scheduler\\Trigger\\JitterTriggerA trigger that adds a random jitter to a given trigger. The jitter is some time that it's added/subtracted to the original triggering date/time. This allows to distribute the load of the scheduled tasks instead of running them all at the exact same time.
Symfony\\Component\\Scheduler\\Trigger\\PeriodicalTriggerA trigger that uses a
DateIntervalto determine the next run date.
The Symfony\\Component\\Scheduler\\Trigger\\JitterTrigger and Symfony\\Component\\Scheduler\\Trigger\\ExcludeTimeTrigger are decorators and modify the behavior of the trigger they wrap. You can get the decorated trigger as well as the decorators by calling the Symfony\\Component\\Scheduler\\Trigger\\AbstractDecoratedTrigger::inner and Symfony\\Component\\Scheduler\\Trigger\\AbstractDecoratedTrigger::decorators methods:
$trigger = new ExcludeTimeTrigger(new JitterTrigger(CronExpressionTrigger::fromSpec('#midnight', new MyMessage()));
$trigger->inner(); // CronExpressionTrigger
$trigger->decorators(); // [ExcludeTimeTrigger, JitterTrigger]Most of them can be created via the Symfony\\Component\\Scheduler\\RecurringMessage class, as shown in the following examples.
Before using cron triggers, you have to install the following dependency:
$ composer require dragonmantank/cron-expressionThen, define the trigger date/time using the same syntax as the cron command-line utility:
RecurringMessage::cron('* * * * *', new Message());
// optionally you can define the timezone used by the cron expression
RecurringMessage::cron('* * * * *', new Message(), new \DateTimeZone('Africa/Malabo'));Tip
Check out the crontab.guru website if you need help to construct/understand cron expressions.
You can also use some special values that represent common cron expressions:
@yearly,@annually- Run once a year, midnight, Jan. 1 -0 0 1 1 *@monthly- Run once a month, midnight, first of month -0 0 1 * *@weekly- Run once a week, midnight on Sun -0 0 * * 0@daily,@midnight- Run once a day, midnight -0 0 * * *@hourly- Run once an hour, first minute -0 * * * *
For example:
RecurringMessage::cron('@daily', new Message());Tip
You can also define cron tasks using the AsCronTask attribute <scheduler-attributes-cron-task>.
If you have many triggers scheduled at same time (for example, at midnight, 0 0 * * *) this will create a very long running list of schedules at that exact time. This may cause an issue if a task has a memory leak.
You can add a hash symbol (#) in expressions to generate random values. Athough the values are random, they are predictable and consistent because they are generated based on the message. A message with string representation my task and a defined frequency of # # * * * will have an idempotent frequency of 56 20 * * * (every day at 8:56pm).
You can also use hash ranges (#(x-y)) to define the list of possible values for that random part. For example, # #(0-7) * * * means daily, some time between midnight and 7am. Using the # without a range creates a range of any valid value for the field. # # # # # is short for #(0-59) #(0-23) #(1-28) #(1-12) #(0-6).
You can also use some special values that represent common hashed cron expressions:
| Alias | Converts to |
|---|---|
#hourly |
# * * * * (at some minute every hour) |
#daily |
# # * * * (at some time every day) |
#weekly |
# # * * # (at some time every week) |
#weekly@midnight |
# #(0-2) * * # (at #midnight one day every week) |
#monthly |
# # # * * (at some time on some day, once per month) |
#monthly@midnight |
# #(0-2) # * * (at #midnight on some day, once per month) |
#annually |
# # # # * (at some time on some day, once per year) |
#annually@midnight |
# #(0-2) # # * (at #midnight on some day, once per year) |
#yearly |
# # # # * alias for #annually |
#yearly@midnight |
# #(0-2) # # * alias for #annually@midnight |
#midnight |
# #(0-2) * * * (at some time between midnight and 2:59am, every day) |
For example:
RecurringMessage::cron('#midnight', new Message());Note
The day of month range is 1-28, this is to account for February which has a minimum of 28 days.
These triggers allows to configure the frequency using different data types (string, integer, DateInterval). They also support the relative formats defined by PHP datetime functions:
RecurringMessage::every('10 seconds', new Message());
RecurringMessage::every('3 weeks', new Message());
RecurringMessage::every('first Monday of next month', new Message());
$from = new \DateTimeImmutable('13:47', new \DateTimeZone('Europe/Paris'));
$until = '2023-06-12';
RecurringMessage::every('first Monday of next month', new Message(), $from, $until);Tip
You can also define periodic tasks using the AsPeriodicTask attribute <scheduler-attributes-periodic-task>.
Custom triggers allow to configure any frequency dynamically. They are created as services that implement Symfony\\Component\\Scheduler\\Trigger\\TriggerInterface.
For example, if you want to send customer reports daily except for holiday periods:
// src/Scheduler/Trigger/NewUserWelcomeEmailHandler.php
namespace App\Scheduler\Trigger;
class ExcludeHolidaysTrigger implements TriggerInterface
{
public function __construct(private TriggerInterface $inner)
{
}
// use this method to give a nice displayable name to
// identify your trigger (it eases debugging)
public function __toString(): string
{
return $this->inner.' (except holidays)';
}
public function getNextRunDate(\DateTimeImmutable $run): ?\DateTimeImmutable
{
if (!$nextRun = $this->inner->getNextRunDate($run)) {
return null;
}
// loop until you get the next run date that is not a holiday
while (!$this->isHoliday($nextRun) {
$nextRun = $this->inner->getNextRunDate($nextRun);
}
return $nextRun;
}
private function isHoliday(\DateTimeImmutable $timestamp): bool
{
// add some logic to determine if the given $timestamp is a holiday
// return true if holiday, false otherwise
}
}Then, define your recurring message:
RecurringMessage::trigger(
new ExcludeHolidaysTrigger(
CronExpressionTrigger::fromSpec('@daily'),
),
new SendDailySalesReports('...'),
);Finally, the recurring messages has to be attached to a schedule:
// src/Scheduler/SaleTaskProvider.php
namespace App\Scheduler;
#[AsSchedule('uptoyou')]
class SaleTaskProvider implements ScheduleProviderInterface
{
public function getSchedule(): Schedule
{
return $this->schedule ??= (new Schedule())
->with(
RecurringMessage::trigger(
new ExcludeHolidaysTrigger(
CronExpressionTrigger::fromSpec('@daily'),
),
new SendDailySalesReports()
),
RecurringMessage::cron('3 8 * * 1', new CleanUpOldSalesReport())
);
}
}So, this RecurringMessage will encompass both the trigger, defining the generation frequency of the message, and the message itself, the one to be processed by a specific handler.
But what is interesting to know is that it also provides you with the ability to generate your message(s) dynamically.
This proves particularly useful when the message depends on data stored in databases or third-party services.
Following the previous example of reports generation: they depend on customer requests. Depending on the specific demands, any number of reports may need to be generated at a defined frequency. For these dynamic scenarios, it gives you the capability to dynamically define our message(s) instead of statically. This is achieved by defining a Symfony\\Component\\Scheduler\\Trigger\\CallbackMessageProvider.
Essentially, this means you can dynamically, at runtime, define your message(s) through a callback that gets executed each time the scheduler transport checks for messages to be generated:
// src/Scheduler/SaleTaskProvider.php
namespace App\Scheduler;
#[AsSchedule('uptoyou')]
class SaleTaskProvider implements ScheduleProviderInterface
{
public function getSchedule(): Schedule
{
return $this->schedule ??= (new Schedule())
->with(
RecurringMessage::trigger(
new ExcludeHolidaysTrigger(
CronExpressionTrigger::fromSpec('@daily'),
),
// instead of being static as in the previous example
new CallbackMessageProvider([$this, 'generateReports'], 'foo')),
RecurringMessage::cron(‘3 8 * * 1’, new CleanUpOldSalesReport())
);
}
public function generateReports(MessageContext $context)
{
// ...
yield new SendDailySalesReports();
yield new ReportSomethingReportSomethingElse();
}
}There is also another way to build a RecurringMessage, and this can be done by adding one of these attributes to a service or a command: Symfony\\Component\\Scheduler\\Attribute\\AsPeriodicTask and Symfony\\Component\\Scheduler\\Attribute\\AsCronTask.
For both of these attributes, you have the ability to define the schedule to use via the scheduleoption. By default, the default named schedule will be used. Also, by default, the __invoke method of your service will be called but, it's also possible to specify the method to call via the methodoption and you can define arguments via argumentsoption if necessary.
This is the most basic way to define a cron trigger with this attribute:
// src/Scheduler/Task/SendDailySalesReports.php
namespace App\Scheduler\Task;
use Symfony\Component\Scheduler\Attribute\AsCronTask;
#[AsCronTask('0 0 * * *')]
class SendDailySalesReports
{
public function __invoke()
{
// ...
}
}The attribute takes more parameters to customize the trigger:
// adds randomly up to 6 seconds to the trigger time to avoid load spikes
#[AsCronTask('0 0 * * *', jitter: 6)]
// defines the method name to call instead as well as the arguments to pass to it
#[AsCronTask('0 0 * * *', method: 'sendEmail', arguments: ['email' => 'admin@example.com'])]
// defines the timezone to use
#[AsCronTask('0 0 * * *', timezone: 'Africa/Malabo')]This is the most basic way to define a periodic trigger with this attribute:
// src/Scheduler/Task/SendDailySalesReports.php
namespace App\Scheduler\Task;
use Symfony\Component\Scheduler\Attribute\AsPeriodicTask;
#[AsPeriodicTask(frequency: '1 day', from: '2022-01-01', until: '2023-06-12')]
class SendDailySalesReports
{
public function __invoke()
{
// ...
}
}Note
The from and until options are optional. If not defined, the task will be executed indefinitely.
The #[AsPeriodicTask] attribute takes many parameters to customize the trigger:
// the frequency can be defined as an integer representing the number of seconds
#[AsPeriodicTask(frequency: 86400)]
// adds randomly up to 6 seconds to the trigger time to avoid load spikes
#[AsPeriodicTask(frequency: '1 day', jitter: 6)]
// defines the method name to call instead as well as the arguments to pass to it
#[AsPeriodicTask(frequency: '1 day', method: 'sendEmail', arguments: ['email' => 'admin@symfony.com'])]
class SendDailySalesReports
{
public function sendEmail(string $email): void
{
// ...
}
}
// defines the timezone to use
#[AsPeriodicTask(frequency: '1 day', timezone: 'Africa/Malabo')]While planning a schedule in advance is beneficial, it is rare for a schedule to remain static over time. After a certain period, some RecurringMessages may become obsolete, while others may need to be integrated into the planning.
As a general practice, to alleviate a heavy workload, the recurring messages in the schedules are stored in memory to avoid recalculation each time the scheduler transport generates messages. However, this approach can have a flip side.
Following the same report generation example as above, the company might do some promotions during specific periods (and they need to be communicated repetitively throughout a given timeframe) or the deletion of old reports needs to be halted under certain circumstances.
This is why the Scheduler incorporates a mechanism to dynamically modify the schedule and consider all changes in real-time.
The schedule provides you with the ability to Symfony\\Component\\Scheduler\Schedule::add, Symfony\\Component\\Scheduler\Schedule::remove, or Symfony\\Component\\Scheduler\Schedule::clear all associated recurring messages, resulting in the reset and recalculation of the in-memory stack of recurring messages.
For instance, for various reasons, if there's no need to generate a report, a callback can be employed to conditionally skip generating of some or all reports.
However, if the intention is to completely remove a recurring message and its recurrence, the Symfony\\Component\\Scheduler\Schedule offers a Symfony\\Component\\Scheduler\Schedule::remove or a Symfony\\Component\\Scheduler\Schedule::removeById method. This can be particularly useful in your case, especially if you need to halt the generation of the recurring message, which involves deleting old reports.
In your handler, you can check a condition and, if affirmative, access the Symfony\\Component\\Scheduler\Schedule and invoke this method:
// src/Scheduler/SaleTaskProvider.php
namespace App\Scheduler;
#[AsSchedule('uptoyou')]
class SaleTaskProvider implements ScheduleProviderInterface
{
public function getSchedule(): Schedule
{
$this->removeOldReports = RecurringMessage::cron(‘3 8 * * 1’, new CleanUpOldSalesReport());
return $this->schedule ??= (new Schedule())
->with(
// ...
$this->removeOldReports;
);
}
// ...
public function removeCleanUpMessage()
{
$this->getSchedule()->getSchedule()->remove($this->removeOldReports);
}
}
// src/Scheduler/Handler/.php
namespace App\Scheduler\Handler;
#[AsMessageHandler]
class CleanUpOldSalesReportHandler
{
public function __invoke(CleanUpOldSalesReport $cleanUpOldSalesReport): void
{
// do some work here...
if ($isFinished) {
$this->mySchedule->removeCleanUpMessage();
}
}
}Nevertheless, this system may not be the most suitable for all scenarios. Also, the handler should ideally be designed to process the type of message it is intended for, without making decisions about adding or removing a new recurring message.
For instance, if, due to an external event, there is a need to add a recurrent message aimed at deleting reports, it can be challenging to achieve within the handler. This is because the handler will no longer be called or executed once there are no more messages of that type.
However, the Scheduler also features an event system that is integrated into a Symfony full-stack application by grafting onto Symfony Messenger events. These events are dispatched through a listener, providing a convenient means to respond.
The goal is to provide flexibility in deciding when to take action while preserving decoupling. Three primary event types have been introduced types
PRE_RUN_EVENTPOST_RUN_EVENTFAILURE_EVENT
Access to the schedule is a crucial feature, allowing effortless addition or removal of message types. Additionally, it will be possible to access the currently processed message and its message context.
In consideration of our scenario, you can listen to the PRE_RUN_EVENT and check if a certain condition is met. For instance, you might decide to add a recurring message for cleaning old reports again, with the same or different configurations, or add any other recurring message(s).
If you had chosen to handle the deletion of the recurring message, you could have done so in a listener for this event. Importantly, it reveals a specific feature Symfony\\Component\\Scheduler\\Event\\PreRunEvent::shouldCancel that allows you to prevent the message of the deleted recurring message from being transferred and processed by its handler:
// src/Scheduler/SaleTaskProvider.php
namespace App\Scheduler;
#[AsSchedule('uptoyou')]
class SaleTaskProvider implements ScheduleProviderInterface
{
public function getSchedule(): Schedule
{
$this->removeOldReports = RecurringMessage::cron('3 8 * * 1', new CleanUpOldSalesReport());
return $this->schedule ??= (new Schedule())
->with(
// ...
);
->before(function(PreRunEvent $event) {
$message = $event->getMessage();
$messageContext = $event->getMessageContext();
// can access the schedule
$schedule = $event->getSchedule()->getSchedule();
// can target directly the RecurringMessage being processed
$schedule->removeById($messageContext->id);
// allow to call the ShouldCancel() and avoid the message to be handled
$event->shouldCancel(true);
}
->after(function(PostRunEvent $event) {
// Do what you want
}
->onFailure(function(FailureEvent $event) {
// Do what you want
}
}
}Event Class: Symfony\\Component\\Scheduler\\Event\\PreRunEvent
PreRunEvent allows to modify the Symfony\\Component\\Scheduler\\Schedule or cancel a message before it's consumed:
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Scheduler\Event\PreRunEvent;
public function onMessage(PreRunEvent $event): void
{
$schedule = $event->getSchedule();
$context = $event->getMessageContext();
$message = $event->getMessage();
// do something with the schedule, context or message
// and/or cancel message
$event->shouldCancel(true);
}Execute this command to find out which listeners are registered for this event and their priorities:
$ php bin/console debug:event-dispatcher "Symfony\Component\Scheduler\Event\PreRunEvent"Event Class: Symfony\\Component\\Scheduler\\Event\\PostRunEvent
PostRunEvent allows to modify the Symfony\\Component\\Scheduler\\Schedule after a message is consumed:
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Scheduler\Event\PostRunEvent;
public function onMessage(PostRunEvent $event): void
{
$schedule = $event->getSchedule();
$context = $event->getMessageContext();
$message = $event->getMessage();
// do something with the schedule, context or message
}Execute this command to find out which listeners are registered for this event and their priorities:
$ php bin/console debug:event-dispatcher "Symfony\Component\Scheduler\Event\PostRunEvent"Event Class: Symfony\\Component\\Scheduler\\Event\\FailureEvent
FailureEvent allows to modify the Symfony\\Component\\Scheduler\\Schedule when a message consumption throws an exception:
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Scheduler\Event\FailureEvent;
public function onMessage(FailureEvent $event): void
{
$schedule = $event->getSchedule();
$context = $event->getMessageContext();
$message = $event->getMessage();
$error = $event->getError();
// do something with the schedule, context, message or error (logging, ...)
// and/or ignore failure event
$event->shouldIgnore(true);
}Execute this command to find out which listeners are registered for this event and their priorities:
$ php bin/console debug:event-dispatcher "Symfony\Component\Scheduler\Event\FailureEvent"After defining and attaching your recurring messages to a schedule, you'll need a mechanism to generate and consume the messages according to their defined frequencies. To do that, the Scheduler component uses the messenger:consume command from the Messenger component:
$ php bin/console messenger:consume scheduler_nameofyourschedule
# use -vv if you need details about what's happening
$ php bin/console messenger:consume scheduler_nameofyourschedule -vv
The debug:scheduler command provides a list of schedules along with their recurring messages. You can narrow down the list to a specific schedule:
$ php bin/console debug:scheduler
Scheduler
=========
default
-------
------------------- ------------------------- ----------------------
Trigger Provider Next Run
------------------- ------------------------- ----------------------
every 2 days App\Messenger\Foo(0:17..) Sun, 03 Dec 2023 ...
15 4 */3 * * App\Messenger\Foo(0:17..) Mon, 18 Dec 2023 ...
-------------------- -------------------------- ---------------------
# you can also specify a date to use for the next run date:
$ php bin/console debug:scheduler --date=2025-10-18
# you can also specify a date to use for the next run date for a schedule:
$ php bin/console debug:scheduler name_of_schedule --date=2025-10-18
# use the --all option to also display the terminated recurring messages
$ php bin/console debug:scheduler --allWhen a worker is restarted or undergoes shutdown for a period, the Scheduler transport won't be able to generate the messages (because they are created on-the-fly by the scheduler transport). This implies that any messages scheduled to be sent during the worker's inactive period are not sent, and the Scheduler will lose track of the last processed message. Upon restart, it will recalculate the messages to be generated from that point onward.
To illustrate, consider a recurring message set to be sent every 3 days. If a worker is restarted on day 2, the message will be sent 3 days from the restart, on day 5.
While this behavior may not necessarily pose a problem, there is a possibility that it may not align with what you are seeking.
That's why the scheduler allows to remember the last execution date of a message via the stateful option (and the Cache component </components/cache>). This allows the system to retain the state of the schedule, ensuring that when a worker is restarted, it resumes from the point it left off.:
// src/Scheduler/SaleTaskProvider.php
namespace App\Scheduler;
#[AsSchedule('uptoyou')]
class SaleTaskProvider implements ScheduleProviderInterface
{
public function getSchedule(): Schedule
{
$this->removeOldReports = RecurringMessage::cron('3 8 * * 1', new CleanUpOldSalesReport());
return $this->schedule ??= (new Schedule())
->with(
// ...
)
->stateful($this->cache)
}
}To scale your schedules more effectively, you can use multiple workers. In such cases, a good practice is to add a lock </components/lock> to prevent the same task more than once:
// src/Scheduler/SaleTaskProvider.php
namespace App\Scheduler;
#[AsSchedule('uptoyou')]
class SaleTaskProvider implements ScheduleProviderInterface
{
public function getSchedule(): Schedule
{
$this->removeOldReports = RecurringMessage::cron('3 8 * * 1', new CleanUpOldSalesReport());
return $this->schedule ??= (new Schedule())
->with(
// ...
)
->lock($this->lockFactory->createLock('my-lock')
}
}Tip
The processing time of a message matters. If it takes a long time, all subsequent message processing may be delayed. So, it's a good practice to anticipate this and plan for frequencies greater than the processing time of a message.
Additionally, for better scaling of your schedules, you have the option to wrap your message in a Symfony\\Component\\Messenger\\Message\\RedispatchMessage. This allows you to specify a transport on which your message will be redispatched before being further redispatched to its corresponding handler:
// src/Scheduler/SaleTaskProvider.php
namespace App\Scheduler;
#[AsSchedule('uptoyou')]
class SaleTaskProvider implements ScheduleProviderInterface
{
public function getSchedule(): Schedule
{
return $this->schedule ??= (new Schedule())
->with(
RecurringMessage::every('5 seconds', new RedispatchMessage(new Message(), 'async'))
);
}
}