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Laravel now offers Horizon, a beautiful dashboard and configuration system for your Redis powered queues. Check out the full Horizon documentation for more information.
Laravel queues provide a unified API across a variety of different queue backends, such as Beanstalk, Amazon SQS, Redis, or even a relational database. Queues allow you to defer the processing of a time consuming task, such as sending an email, until a later time. Deferring these time consuming tasks drastically speeds up web requests to your application.
The queue configuration file is stored in config/queue.php
. In this file you will find connection configurations for each of the queue drivers that are included with the framework, which includes a database, Beanstalkd, Amazon SQS, Redis, and a synchronous driver that will execute jobs immediately (for local use). A null
queue driver is also included which discards queued jobs.
Before getting started with Laravel queues, it is important to understand the distinction between "connections" and "queues". In your config/queue.php
configuration file, there is a connections
configuration option. This option defines a particular connection to a backend service such as Amazon SQS, Beanstalk, or Redis. However, any given queue connection may have multiple "queues" which may be thought of as different stacks or piles of queued jobs.
Note that each connection configuration example in the queue
configuration file contains a queue
attribute. This is the default queue that jobs will be dispatched to when they are sent to a given connection. In other words, if you dispatch a job without explicitly defining which queue it should be dispatched to, the job will be placed on the queue that is defined in the queue
attribute of the connection configuration:
Some applications may not need to ever push jobs onto multiple queues, instead preferring to have one simple queue. However, pushing jobs to multiple queues can be especially useful for applications that wish to prioritize or segment how jobs are processed, since the Laravel queue worker allows you to specify which queues it should process by priority. For example, if you push jobs to a high
queue, you may run a worker that gives them higher processing priority:
Database
In order to use the database
queue driver, you will need a database table to hold the jobs. To generate a migration that creates this table, run the queue:table
Artisan command. Once the migration has been created, you may migrate your database using the migrate
command:
Redis
In order to use the redis
queue driver, you should configure a Redis database connection in your config/database.php
configuration file.
Redis Cluster
If your Redis queue connection uses a Redis Cluster, your queue names must contain a key hash tag. This is required in order to ensure all of the Redis keys for a given queue are placed into the same hash slot:
Blocking
When using the Redis queue, you may use the block_for
configuration option to specify how long the driver should wait for a job to become available before iterating through the worker loop and re-polling the Redis database.
Adjusting this value based on your queue load can be more efficient than continually polling the Redis database for new jobs. For instance, you may set the value to 5
to indicate that the driver should block for five seconds while waiting for a job to become available:
Setting
block_for
to0
will cause queue workers to block indefinitely until a job is available. This will also prevent signals such asSIGTERM
from being handled until the next job has been processed.
Other Driver Prerequisites
The following dependencies are needed for the listed queue drivers:
Amazon SQS:
aws/aws-sdk-php ~3.0
Beanstalkd:
pda/pheanstalk ~4.0
Redis:
predis/predis ~1.0
or phpredis PHP extension
By default, all of the queueable jobs for your application are stored in the app/Jobs
directory. If the app/Jobs
directory doesn't exist, it will be created when you run the make:job
Artisan command. You may generate a new queued job using the Artisan CLI:
The generated class will implement the Illuminate\Contracts\Queue\ShouldQueue
interface, indicating to Laravel that the job should be pushed onto the queue to run asynchronously.
Job stubs may be customized using stub publishing
Job classes are very simple, normally containing only a handle
method which is called when the job is processed by the queue. To get started, let's take a look at an example job class. In this example, we'll pretend we manage a podcast publishing service and need to process the uploaded podcast files before they are published:
In this example, note that we were able to pass an Eloquent model directly into the queued job's constructor. Because of the SerializesModels
trait that the job is using, Eloquent models and their loaded relationships will be gracefully serialized and unserialized when the job is processing. If your queued job accepts an Eloquent model in its constructor, only the identifier for the model will be serialized onto the queue. When the job is actually handled, the queue system will automatically re-retrieve the full model instance and its loaded relationships from the database. It's all totally transparent to your application and prevents issues that can arise from serializing full Eloquent model instances.
The handle
method is called when the job is processed by the queue. Note that we are able to type-hint dependencies on the handle
method of the job. The Laravel service container automatically injects these dependencies.
If you would like to take total control over how the container injects dependencies into the handle
method, you may use the container's bindMethod
method. The bindMethod
method accepts a callback which receives the job and the container. Within the callback, you are free to invoke the handle
method however you wish. Typically, you should call this method from a service provider:
Binary data, such as raw image contents, should be passed through the
base64_encode
function before being passed to a queued job. Otherwise, the job may not properly serialize to JSON when being placed on the queue.
Handling Relationships
Because loaded relationships also get serialized, the serialized job string can become quite large. To prevent relations from being serialized, you can call the withoutRelations
method on the model when setting a property value. This method will return an instance of the model with no loaded relationships:
Job middleware allow you to wrap custom logic around the execution of queued jobs, reducing boilerplate in the jobs themselves. For example, consider the following handle
method which leverages Laravel's Redis rate limiting features to allow only one job to process every five seconds:
While this code is valid, the structure of the handle
method becomes noisy since it is cluttered with Redis rate limiting logic. In addition, this rate limiting logic must be duplicated for any other jobs that we want to rate limit.
Instead of rate limiting in the handle method, we could define a job middleware that handles rate limiting. Laravel does not have a default location for job middleware, so you are welcome to place job middleware anywhere in your application. In this example, we will place the middleware in a app/Jobs/Middleware
directory:
As you can see, like route middleware, job middleware receive the job being processed and a callback that should be invoked to continue processing the job.
After creating job middleware, they may be attached to a job by returning them from the job's middleware
method. This method does not exist on jobs scaffolded by the make:job
Artisan command, so you will need to add it to your own job class definition:
Once you have written your job class, you may dispatch it using the dispatch
method on the job itself. The arguments passed to the dispatch
method will be given to the job's constructor:
If you would like to conditionally dispatch a job, you may use the dispatchIf
and dispatchUnless
methods:
If you would like to delay the execution of a queued job, you may use the delay
method when dispatching a job. For example, let's specify that a job should not be available for processing until 10 minutes after it has been dispatched:
The Amazon SQS queue service has a maximum delay time of 15 minutes.
Dispatching After The Response Is Sent To Browser
Alternatively, the dispatchAfterResponse
method delays dispatching a job until after the response is sent to the user's browser. This will still allow the user to begin using the application even though a queued job is still executing. This should typically only be used for jobs that take about a second, such as sending an email:
You may dispatch
a Closure and chain the afterResponse
method onto the helper to execute a Closure after the response has been sent to the browser:
If you would like to dispatch a job immediately (synchronously), you may use the dispatchNow
method. When using this method, the job will not be queued and will be run immediately within the current process:
Job chaining allows you to specify a list of queued jobs that should be run in sequence after the primary job has executed successfully. If one job in the sequence fails, the rest of the jobs will not be run. To execute a queued job chain, you may use the withChain
method on any of your dispatchable jobs:
In addition to chaining job class instances, you may also chain Closures:
Deleting jobs using the
$this->delete()
method will not prevent chained jobs from being processed. The chain will only stop executing if a job in the chain fails.
Chain Connection & Queue
If you would like to specify the default connection and queue that should be used for the chained jobs, you may use the allOnConnection
and allOnQueue
methods. These methods specify the queue connection and queue name that should be used unless the queued job is explicitly assigned a different connection / queue:
Dispatching To A Particular Queue
By pushing jobs to different queues, you may "categorize" your queued jobs and even prioritize how many workers you assign to various queues. Keep in mind, this does not push jobs to different queue "connections" as defined by your queue configuration file, but only to specific queues within a single connection. To specify the queue, use the onQueue
method when dispatching the job:
Dispatching To A Particular Connection
If you are working with multiple queue connections, you may specify which connection to push a job to. To specify the connection, use the onConnection
method when dispatching the job:
You may chain the onConnection
and onQueue
methods to specify the connection and the queue for a job:
Max Attempts
One approach to specifying the maximum number of times a job may be attempted is via the --tries
switch on the Artisan command line:
However, you may take a more granular approach by defining the maximum number of attempts on the job class itself. If the maximum number of attempts is specified on the job, it will take precedence over the value provided on the command line:
Time Based Attempts
As an alternative to defining how many times a job may be attempted before it fails, you may define a time at which the job should timeout. This allows a job to be attempted any number of times within a given time frame. To define the time at which a job should timeout, add a retryUntil
method to your job class:
You may also define a
retryUntil
method on your queued event listeners.
Max Exceptions
Sometimes you may wish to specify that a job may be attempted many times, but should fail if the retries are triggered by a given number of exceptions. To accomplish this, you may define a maxExceptions
property on your job class:
In this example, the job is released for ten seconds if the application is unable to obtain a Redis lock and will continue to be retried up to 25 times. However, the job will fail if three unhandled exceptions are thrown by the job.
Timeout
The
timeout
feature is optimized for PHP 7.1+ and thepcntl
PHP extension.
Likewise, the maximum number of seconds that jobs can run may be specified using the --timeout
switch on the Artisan command line:
However, you may also define the maximum number of seconds a job should be allowed to run on the job class itself. If the timeout is specified on the job, it will take precedence over any timeout specified on the command line:
This feature requires that your application can interact with a Redis server.
If your application interacts with Redis, you may throttle your queued jobs by time or concurrency. This feature can be of assistance when your queued jobs are interacting with APIs that are also rate limited.
For example, using the throttle
method, you may throttle a given type of job to only run 10 times every 60 seconds. If a lock can not be obtained, you should typically release the job back onto the queue so it can be retried later:
In the example above, the
key
may be any string that uniquely identifies the type of job you would like to rate limit. For example, you may wish to construct the key based on the class name of the job and the IDs of the Eloquent models it operates on.Releasing a throttled job back onto the queue will still increment the job's total number of
attempts
.
Alternatively, you may specify the maximum number of workers that may simultaneously process a given job. This can be helpful when a queued job is modifying a resource that should only be modified by one job at a time. For example, using the funnel
method, you may limit jobs of a given type to only be processed by one worker at a time:
When using rate limiting, the number of attempts your job will need to run successfully can be hard to determine. Therefore, it is useful to combine rate limiting with time based attempts.
If an exception is thrown while the job is being processed, the job will automatically be released back onto the queue so it may be attempted again. The job will continue to be released until it has been attempted the maximum number of times allowed by your application. The maximum number of attempts is defined by the --tries
switch used on the queue:work
Artisan command. Alternatively, the maximum number of attempts may be defined on the job class itself. More information on running the queue worker can be found below.
Instead of dispatching a job class to the queue, you may also dispatch a Closure. This is great for quick, simple tasks that need to be executed outside of the current request cycle:
When dispatching Closures to the queue, the Closure's code contents is cryptographically signed so it can not be modified in transit.
Laravel includes a queue worker that will process new jobs as they are pushed onto the queue. You may run the worker using the queue:work
Artisan command. Note that once the queue:work
command has started, it will continue to run until it is manually stopped or you close your terminal:
To keep the
queue:work
process running permanently in the background, you should use a process monitor such as Supervisor to ensure that the queue worker does not stop running.
Remember, queue workers are long-lived processes and store the booted application state in memory. As a result, they will not notice changes in your code base after they have been started. So, during your deployment process, be sure to restart your queue workers. In addition, remember that any static state created or modified by your application will not be automatically reset between jobs.
Alternatively, you may run the queue:listen
command. When using the queue:listen
command, you don't have to manually restart the worker when you want to reload your updated code or reset the application state; however, this command is not as efficient as queue:work
:
Specifying The Connection & Queue
You may also specify which queue connection the worker should utilize. The connection name passed to the work
command should correspond to one of the connections defined in your config/queue.php
configuration file:
You may customize your queue worker even further by only processing particular queues for a given connection. For example, if all of your emails are processed in an emails
queue on your redis
queue connection, you may issue the following command to start a worker that only processes that queue:
Processing A Single Job
The --once
option may be used to instruct the worker to only process a single job from the queue:
Processing All Queued Jobs & Then Exiting
The --stop-when-empty
option may be used to instruct the worker to process all jobs and then exit gracefully. This option can be useful when working Laravel queues within a Docker container if you wish to shutdown the container after the queue is empty:
Resource Considerations
Daemon queue workers do not "reboot" the framework before processing each job. Therefore, you should free any heavy resources after each job completes. For example, if you are doing image manipulation with the GD library, you should free the memory with imagedestroy
when you are done.
Sometimes you may wish to prioritize how your queues are processed. For example, in your config/queue.php
you may set the default queue
for your redis
connection to low
. However, occasionally you may wish to push a job to a high
priority queue like so:
To start a worker that verifies that all of the high
queue jobs are processed before continuing to any jobs on the low
queue, pass a comma-delimited list of queue names to the work
command:
Since queue workers are long-lived processes, they will not pick up changes to your code without being restarted. So, the simplest way to deploy an application using queue workers is to restart the workers during your deployment process. You may gracefully restart all of the workers by issuing the queue:restart
command:
This command will instruct all queue workers to gracefully "die" after they finish processing their current job so that no existing jobs are lost. Since the queue workers will die when the queue:restart
command is executed, you should be running a process manager such as Supervisor to automatically restart the queue workers.
The queue uses the cache to store restart signals, so you should verify a cache driver is properly configured for your application before using this feature.
Job Expiration
In your config/queue.php
configuration file, each queue connection defines a retry_after
option. This option specifies how many seconds the queue connection should wait before retrying a job that is being processed. For example, if the value of retry_after
is set to 90
, the job will be released back onto the queue if it has been processing for 90 seconds without being deleted. Typically, you should set the retry_after
value to the maximum number of seconds your jobs should reasonably take to complete processing.
The only queue connection which does not contain a
retry_after
value is Amazon SQS. SQS will retry the job based on the Default Visibility Timeout which is managed within the AWS console.
Worker Timeouts
The queue:work
Artisan command exposes a --timeout
option. The --timeout
option specifies how long the Laravel queue master process will wait before killing off a child queue worker that is processing a job. Sometimes a child queue process can become "frozen" for various reasons. The --timeout
option removes frozen processes that have exceeded that specified time limit:
The retry_after
configuration option and the --timeout
CLI option are different, but work together to ensure that jobs are not lost and that jobs are only successfully processed once.
The
--timeout
value should always be at least several seconds shorter than yourretry_after
configuration value. This will ensure that a worker processing a given job is always killed before the job is retried. If your--timeout
option is longer than yourretry_after
configuration value, your jobs may be processed twice.
Worker Sleep Duration
When jobs are available on the queue, the worker will keep processing jobs with no delay in between them. However, the sleep
option determines how long (in seconds) the worker will "sleep" if there are no new jobs available. While sleeping, the worker will not process any new jobs - the jobs will be processed after the worker wakes up again.
Installing Supervisor
Supervisor is a process monitor for the Linux operating system, and will automatically restart your queue:work
process if it fails. To install Supervisor on Ubuntu, you may use the following command:
If configuring Supervisor yourself sounds overwhelming, consider using Laravel Forge, which will automatically install and configure Supervisor for your Laravel projects.
Configuring Supervisor
Supervisor configuration files are typically stored in the /etc/supervisor/conf.d
directory. Within this directory, you may create any number of configuration files that instruct supervisor how your processes should be monitored. For example, let's create a laravel-worker.conf
file that starts and monitors a queue:work
process:
In this example, the numprocs
directive will instruct Supervisor to run 8 queue:work
processes and monitor all of them, automatically restarting them if they fail. You should change the queue:work sqs
portion of the command
directive to reflect your desired queue connection.
You should ensure that the value of
stopwaitsecs
is greater than the number of seconds consumed by your longest running job. Otherwise, Supervisor may kill the job before it is finished processing.
Starting Supervisor
Once the configuration file has been created, you may update the Supervisor configuration and start the processes using the following commands:
For more information on Supervisor, consult the Supervisor documentation.
Sometimes your queued jobs will fail. Don't worry, things don't always go as planned! Laravel includes a convenient way to specify the maximum number of times a job should be attempted. After a job has exceeded this amount of attempts, it will be inserted into the failed_jobs
database table. To create a migration for the failed_jobs
table, you may use the queue:failed-table
command:
Then, when running your queue worker, you can specify the maximum number of times a job should be attempted using the --tries
switch on the queue:work
command. If you do not specify a value for the --tries
option, jobs will only be attempted once:
In addition, you may specify how many seconds Laravel should wait before retrying a job that has failed using the --delay
option. By default, a job is retried immediately:
If you would like to configure the failed job retry delay on a per-job basis, you may do so by defining a retryAfter
property on your queued job class:
If you require more complex logic for determining the retry delay, you may define a retryAfter
method on your queued job class:
You may define a failed
method directly on your job class, allowing you to perform job specific clean-up when a failure occurs. This is the perfect location to send an alert to your users or revert any actions performed by the job. The Exception
that caused the job to fail will be passed to the failed
method:
The
failed
method will not be called if the job was dispatched using thedispatchNow
method.
If you would like to register an event that will be called when a job fails, you may use the Queue::failing
method. This event is a great opportunity to notify your team via email or Slack. For example, we may attach a callback to this event from the AppServiceProvider
that is included with Laravel:
To view all of your failed jobs that have been inserted into your failed_jobs
database table, you may use the queue:failed
Artisan command:
The queue:failed
command will list the job ID, connection, queue, failure time, and other information about the job. The job ID may be used to retry the failed job. For instance, to retry a failed job that has an ID of 5
, issue the following command:
If necessary, you may pass multiple IDs or an ID range (when using numeric IDs) to the command:
To retry all of your failed jobs, execute the queue:retry
command and pass all
as the ID:
If you would like to delete a failed job, you may use the queue:forget
command:
To delete all of your failed jobs, you may use the queue:flush
command:
When injecting an Eloquent model into a job, it is automatically serialized before being placed on the queue and restored when the job is processed. However, if the model has been deleted while the job was waiting to be processed by a worker, your job may fail with a ModelNotFoundException
.
For convenience, you may choose to automatically delete jobs with missing models by setting your job's deleteWhenMissingModels
property to true
:
Using the before
and after
methods on the Queue
facade, you may specify callbacks to be executed before or after a queued job is processed. These callbacks are a great opportunity to perform additional logging or increment statistics for a dashboard. Typically, you should call these methods from a service provider. For example, we may use the AppServiceProvider
that is included with Laravel:
Using the looping
method on the Queue
facade, you may specify callbacks that execute before the worker attempts to fetch a job from a queue. For example, you might register a Closure to rollback any transactions that were left open by a previously failed job:
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