Task Manager

Kibana Task Manager is leveraged by features such as Alerting, Actions, and Reporting to run mission critical work as persistent background tasks. These background tasks distribute work across multiple Kibana instances. This has three major benefits:

Kibana background tasks are managed as follows:

Elasticsearch and Kibana instances use the system clock to determine the current time. To ensure schedules are triggered when expected, synchronize the clocks of all nodes in the cluster using a time service such as Network Time Protocol.

How you deploy Kibana largely depends on your use case. Predicting the throughout a deployment might require to support Task Management is difficult because features can schedule an unpredictable number of tasks at a variety of scheduled cadences.

However, there is a relatively straight forward method you can follow to produce a rough estimate based on your expected usage.

By default, Kibana polls for tasks at a rate of 10 tasks every 3 seconds. This means that you can expect a single Kibana instance to support up to 200 tasks per minute (200/tpm).

In practice, a Kibana instance will only achieve the upper bound of 200/tpm if the duration of task execution is below the polling rate of 3 seconds. For the most part, the duration of tasks is below that threshold, but it can vary greatly as Elasticsearch and Kibana usage grow and task complexity increases (such as alerts executing heavy queries across large datasets).

By estimating a rough throughput requirment, you can estimate the number of Kibana instances required to reliably execute tasks in a timely manner. An appropriate number of Kibana instances can be estimated to match the required scale.

For details on monitoring the health of Kibana Task Manager, follow the guidance in Health monitoring.

At times, the sustainable approach might be to expand the throughput of your cluster by provisioning additional Kibana instances. By default, each additional Kibana instance will add an additional 10 tasks that your cluster can run concurrently, but you can also scale each Kibana instance vertically, if your diagnosis indicates that they can handle the additional workload.

Other times it, might be preferable to increase the throughput of individual Kibana instances.

Tweak the Max Workers via the xpack.task_manager.max_workers setting, which allows each Kibana to pull a higher number of tasks per interval. This could impact the performance of each Kibana instance as the workload will be higher.

Tweak the Poll Interval via the xpack.task_manager.poll_interval setting, which allows each Kibana to pull scheduled tasks at a higher rate. This could impact the performance of the Elasticsearch cluster as the workload will be higher.

Each scaling strategy comes with its own considerations, and the appropriate strategy largely depends on your use case.

Scaling Kibana instances vertically causes higher resource usage in each Kibana instance, as it will perform more concurrent work. Scaling Kibana instances horizontally requires a higher degree of coordination, which can impact overall performance.

A recommended strategy is to follow these steps:

Task Manager, like the rest of the Elastic Stack, is designed to scale horizontally. Take advantage of this ability to ensure mission critical services, such as Alerting and Reporting, always have the capacity they need.

Scaling horizontally requires a higher degree of coordination between Kibana instances. One way Task Manager coordinates with other instances is by delaying its polling schedule to avoid conflicts with other instances. By using health monitoring to evaluate the date of the last_polling_delay across a deployment, you can estimate the frequency at which Task Manager resets its delay mechanism. A higher frequency suggests Kibana instances conflict at a high rate, which you can address by scaling vertically rather than horizontally, reducing the required coordination.

Predicting the required throughput a deployment might need to support Task Management is difficult, as features can schedule an unpredictable number of tasks at a variety of scheduled cadences. However, a rough lower bound can be estimated, which is then used as a guide.

Throughput is best thought of as a measurements in tasks per minute.

A default Kibana instance can support up to 200/tpm.

As demonstrated in Evaluate your capacity estimation, the Task Manager health monitoring performs these estimations automatically.

These estimates are based on historical data and should not be used as predictions, but can be used as a rough guide when scaling the system.

We recommend provisioning enough Kibana instances to ensure a buffer between the observed maximum throughput (as estimated under observed.max_throughput_per_minute) and the average required throughput (as estimated under observed.avg_required_throughput_per_minute). Otherwise there might be insufficient capacity to handle spikes of ad-hoc tasks. How much of a buffer is needed largely depends on your use case, but keep in mind that estimated throughput takes into account recent spikes and, as long as they are representative of your system’s behaviour, shouldn’t require much of a buffer.

We recommend provisioning at least as many Kibana instances as proposed by proposed.provisioned_kibana, but keep in mind that this number is based on the estimated required throughput, which is based on average historical performance, and cannot accurately predict future requirements.

By evaluating the workload, you can make a rough estimate as to the required throughput as a tasks per minute measurement.

For example, suppose your current workload reveals a required throughput of 440/tpm. You can address this scale by provisioning 3 Kibana instances, with an upper throughput of 600/tpm. This scale would provide aproximately 25% additional capacity to handle ad-hoc non-recurring tasks and potential growth in recurring tasks.

Given a deployment of 100 recurring tasks, estimating the required throughput depends on the scheduled cadence. Suppose you expect to run 50 tasks at a cadence of 10s, the other 50 tasks at 20m. In addition, you expect a couple dozen non-recurring tasks every minute.

A non-recurring task requires a single execution, which means that a single Kibana instance could execute all 100 tasks in less than a minute, using only half of its capacity. As these tasks are only executed once, the Kibana instance will sit idle once all tasks are executed. For that reason, don’t include non-recurring tasks in your tasks per minute calculation. Instead, include a buffer in the final lower bound to incur the cost of ad-hoc non-recurring tasks.

A recurring task requires as many executions as its cadence can fit in a minute. A recurring task with a 10s schedule will require 6/tpm, as it will execute 6 times per minute. A recurring task with a 20m schedule only executes 3 times per hour and only requires a throughput of 0.05/tpm, a number so small it that is difficult to take it into account.

For this reason, we recommend grouping tasks by tasks per minute and tasks per hour, as demonstrated in Evaluate your workload, averaging the per hour measurement across all minutes.

It is highly recommended that you maintain at least 20% additional capacity, beyond your expected workload, as spikes in ad-hoc tasks is possible at times of high activity (such as a spike in actions in response to an active alert).

Given the predicted workload, you can estimate a lower bound throughput of 340/tpm (6/tpm * 50 + 3/tph * 50 + 20% buffer). As a default, a Kibana instance provides a throughput of 200/tpm. A good starting point for your deployment is to provision 2 Kibana instances. You could then monitor their performance and reassess as the required throughput becomes clearer.

Although this is a rough estimate, the tasks per minute provides the lower bound needed to execute tasks on time.

Once you estimate tasks per minute , add a buffer for non-recurring tasks. How much of a buffer is required largely depends on your use case. Ensure enough of a buffer is provisioned by evaluating your workload as it grows and tracking the ratio of recurring to non-recurring tasks by evaluating your runtime.