---
title: "Pyroscope query-scheduler | Grafana Pyroscope documentation"
description: "The query-scheduler distributes work to queriers."
---

# Pyroscope query-scheduler

> Note
> 
> The query-scheduler is a v1 architecture component. In v2, the [query frontend](/docs/pyroscope/latest/reference-pyroscope-v2-architecture/components/query-frontend/) communicates directly with [query backends](/docs/pyroscope/latest/reference-pyroscope-v2-architecture/components/query-backend/) without an intermediary scheduler.

The query-scheduler is a stateless component that retains a queue of queries to execute, and distributes the workload to available [queriers](../querier/).

The query-scheduler is a required component when using the [query-frontend](../query-frontend/).

The following flow describes how a query moves through a Pyroscope cluster:

1. The [query-frontend](../query-frontend/) receives queries, and then either splits and shards them, or serves them from the cache.
2. The query-frontend enqueues the queries into a query-scheduler.
3. The query-scheduler stores the queries in an in-memory queue where they wait for a querier to pick them up.
4. Queriers pick up the queries, and executes them.
5. The querier sends results back to query-frontend, which then forwards the results to the client.

## Benefits of using the query-scheduler

Query-scheduler enables the scaling of query-frontends. To learn more, see Mimir [Query Frontend](/docs/mimir/latest/operators-guide/architecture/components/query-frontend/#why-query-frontend-scalability-is-limited) documentation.

## Configuration

To use the query-scheduler, query-frontends and queriers need to discover the addresses of query-scheduler instances. To advertise itself, the query-scheduler uses Ring-based service discovery which is configured via the [memberlist configuration](../../../configure-server/configuring-memberlist/).

## Operational considerations

For high-availability, run two query-scheduler replicas.