Cron - Not running multiple instances of a job

Inizia individuando la gestione del tick dello scheduler, il punto di ingresso ICronJob e le chiamate a job.Run(stoppingToken). Traccia il modo in cui i job pianificati vengono selezionati e monitorati. Il lavoro è completato quando un job pianificato non viene avviato nuovamente mentre la sua attività precedente è ancora in esecuzione, mentre le esecuzioni successive possono iniziare dopo il completamento.

This is not an elaborate solution, but it works (in theory). You can't choose to have multiple instances running or not. I just assumed not to have multiple instances running regardless. I assumed this is not required unless you are running a job every minute or two.

I added a field to the scheduler that tracks the Task returned by job.Run(stoppingToken);. On ever tick check the list for completed tasks and clear them. Prior to running a job skip if it is on the list of running jobs.

I'm sure this might need some tweaking this was my first attempt at it.

private Dictionary<string, Task> _runningJobs;

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// Clear completed jobs
foreach (var key in _runningJobs.Keys)
{
    if (_runningJobs[key].IsCompleted)
    {
        _runningJobs[key].Dispose();
        _runningJobs.Remove(key);
    }
}

// Run jobs that are in the map
RunActiveJobs(runMap, now, stoppingToken);

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foreach (var run in currentRuns)
{

    // We are sure (thanks to our extension method)
    // that the service is of type ICronJob
    var job = (ICronJob)_serviceProvider.GetRequiredService(run);
    string jobName = job.GetType().Name;

    // Continue to next job if job is already running
    if (_runningJobs.ContainsKey(jobName))
    {
        continue;
    }

    // We don't want to await jobs explicitly because that
    // could interfere with other job runs
    var task = job.Run(stoppingToken);

    // Add task to running jobs
    _runningJobs.Add(jobName, task);
}