SkipWhenPreviousJobIsRunningAttribute.cs

SkipWhenPreviousJobIsRunningAttribute.cs

// Zero-Clause BSD (more permissive than MIT, doesn't require copyright notice)
// 
// Permission to use, copy, modify, and/or distribute this software for any purpose
// with or without fee is hereby granted.
// 
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
// OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
// TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
// THIS SOFTWARE.

// Hangfire.Core 1.8+ is required, for previous versions please see revision from year 2022.

using System;
using System.Collections.Generic;
using Hangfire.Client;
using Hangfire.Common;
using Hangfire.States;
using Hangfire.Storage;

namespace ConsoleApp28
{
    public class SkipWhenPreviousJobIsRunningAttribute : JobFilterAttribute, IClientFilter, IApplyStateFilter
    {
        public void OnCreating(CreatingContext context)
        {
            // We can't handle old storages
            if (!(context.Connection is JobStorageConnection connection)) return;

            // We should run this filter only for background jobs based on 
            // recurring ones
            if (!context.Parameters.TryGetValue("RecurringJobId", out var parameter)) return;

            var recurringJobId = parameter as string;

            // RecurringJobId is malformed. This should not happen, but anyway.
            if (String.IsNullOrWhiteSpace(recurringJobId)) return;

            var running = connection.GetValueFromHash($"recurring-job:{recurringJobId}", "Running");
            if ("yes".Equals(running, StringComparison.OrdinalIgnoreCase))
            {
                context.Canceled = true;
            }
        }

        public void OnCreated(CreatedContext filterContext)
        {
        }

        public void OnStateApplied(ApplyStateContext context, IWriteOnlyTransaction transaction)
        {
            if (context.NewState is EnqueuedState)
            {
                ChangeRunningState(context, "yes");
            }
            else if ((context.NewState.IsFinal && !FailedState.StateName.Equals(context.OldStateName, StringComparison.OrdinalIgnoreCase)) || 
                     (context.NewState is FailedState))
            {
                ChangeRunningState(context, "no");
            }
        }

        public void OnStateUnapplied(ApplyStateContext context, IWriteOnlyTransaction transaction)
        {
        }

        private static void ChangeRunningState(ApplyStateContext context, string state)
        {
            // We can't handle old storages
            if (!(context.Connection is JobStorageConnection connection)) return;

            // Obtaining a recurring job identifier
            var recurringJobId = context.GetJobParameter<string>("RecurringJobId", allowStale: true);
            if (String.IsNullOrWhiteSpace(recurringJobId)) return;

            if (context.Storage.HasFeature(JobStorageFeatures.Transaction.AcquireDistributedLock))
            {
                // Acquire a lock in newer storages to avoid race conditions
                ((JobStorageTransaction)context.Transaction).AcquireDistributedLock(
                    $"lock:recurring-job:{recurringJobId}",
                    TimeSpan.FromSeconds(5));
            }

            // Checking whether recurring job exists
            var recurringJob = connection.GetValueFromHash($"recurring-job:{recurringJobId}", "Job");
            if (String.IsNullOrEmpty(recurringJob)) return;

            // Changing the running state
            context.Transaction.SetRangeInHash(
                $"recurring-job:{recurringJobId}",
                new[] { new KeyValuePair<string, string>("Running", state) });
        }
    }
}

Thank you a lot, saved me against PostgreSqlDistributedLockException

@frozzen10 The issue you're experiencing might be because the "Running" status of the job is not being reset properly when the job fails or when it's in a final state. This could cause the job to be immediately canceled on the next execution because the system thinks it's still running. To fix this, you should ensure that the "Running" status is reset in all cases when the job is in a final state, not just when it's not in a FailedState.

in OnStateApplied ` var recurringJobId = SerializationHelper.Deserialize( context.Connection.GetJobParameter(context.BackgroundJob.Id, "RecurringJobId"));

if (string.IsNullOrWhiteSpace(recurringJobId)) return;

if (context.NewState is EnqueuedState) { transaction.SetRangeInHash( $"recurring-job:{recurringJobId}", new[] {new KeyValuePair&lt;string, string&gt;("Running", "yes")}); } else if (context.NewState.IsFinal) { transaction.SetRangeInHash( $"recurring-job:{recurringJobId}", new[] {new KeyValuePair<string, string>("Running", "no")}); } `

Watch out, "Failed state" is not a final state, if you disabled automaticRetry with no delete you'll never have a "DeletedState".
According to your case, please add

context.NewState.IsFinal || context.NewState is FailedState

Is there a new fixed version for this attribute? Why is it not part of Hangfire?

This filter is incredibly helpful, especially for recurring jobs prone to transient errors. We've implemented it for our data import jobs, which poll a somewhat unstable service every 5 minutes.

Previously, we tried:

• DisableConcurrentExecutionAttribute, which worked as expected to prevent concurrent executions.
• AutomaticRetryAttribute(0, Fail), but this wasn't ideal because we rely on monitoring failed jobs after a set number of retries.
• Allowing the 5-minute jobs to flood the queue and retry for up to half an hour, which overloaded the target service.

This filter solved our problem perfectly. It prevents new job triggers based on the interval while a previous instance is still running, even if it's failing multiple times.

It would be fantastic to see this included in the core package!

Jokes apart, I can't pick a meaningful short name for this filter that defines its behavior and tells us it works only with recurring jobs. This is now the only thing that prevents from including it to Hangfire.Core 🤦‍♂️.

@odinserj SerializedRecurringJobAttribute which would actually be used as just [SerializedRecurringJob] in the code using that attribute. The same term and concept are being used for Serializable transaction isolation levels in database management systems and it pretty much refers to the analogous context. See https://en.wikipedia.org/wiki/Isolation_(database_systems)#Serializable where it states:

A serial execution is one in which each SQL-transaction executes to completion before the next SQL-transaction begins.

@odinserj, if i may recommend: SingleInstanceRecurringJobAttribute

Am I right, that this attribute would not prevent a recurring job to be run when the job was already manually triggered by a user?

In my case I've had a problem when a concurrent job was stuck in kind of "loop" (so sometimes the job was stuck and didn't run at all for hours,days..), that was because I was making a lot "Task.Run(...)" in other services which are not related to Hangfire, so I simply moved most of my Task.Run to System.Threading.Channels.Channel and all works well now

It's works perfect. Many thanks.

But it not work if you place the attribute in a interface.

This is OK

[SkipWhenPreviousJobIsRunning]
public class JobWithITaskDelay90Sec : ITask<bool>

This not working.

public class JobWithITaskDelay90Sec : ITask<bool>
{
}

[SkipWhenPreviousJobIsRunning]
public interface ITask<TResult>
{
}

Thank you for providing this code. It perfectly matches the functionality I was looking for.

Unfortunately, it doesn't work for me. Initially, it seemed to work fine on my local setup with a single Hangfire instance, although I didn't test it for very long.

Now that I've deployed it to four test instances, I'm seeing multiple instances of the same RecurringJob running simultaneously. I created a dummy job with Task.Delay for 10 minutes, which starts every minute. It ran overnight, and the test instances were restarted by IIS at some point during the night. Now, I have multiple instances of this job running concurrently.

I'm curious about how this differs from Hangfire Ace's concurrency and throttling via mutex?