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to be removed in Solr 9.0 (see SOLR-14656)
Simulated environment for autoscaling.

See: Description

Package Description

Simulated environment for autoscaling.


Simulated SolrCloudManager - SimCloudManager

This implementation of SolrCloudManager uses the following simulated components: SimCloudManager also maintains an up-to-date /live_nodes in SimDistribStateManager, provides a SolrClient instance for use in tests, and provides several convenience methods for setting up simulated clusters, populating node and replica metrics, collecting autoscaling-related event history, collecting autoscaling event statistics, etc. SimCloudManager runs actual OverseerTriggerThread so that it uses real trigger and trigger action implementations, as well as real event scheduling and processing code. It also provides methods for simulating Overseer leader change. An important part of the SimCloudManager is also a request handler that processes common autoscaling and collection admin requests. Autoscaling requests are processes by an instance of AutoScalingHandler (and result in changes in respective data stored in SimDistribStateManager). Collection admin commands are simulated, ie. they don't use actual CollectionsHandler due to the complex dependencies on real components.


This components maintains collection and replica states:


This component maintains node metrics. When a simulated cluster is set up using eg. SimCloudManager.createCluster(int, org.apache.solr.common.util.TimeSource) method, each simulated node is initialized with some basic metrics that are expected by the autoscaling framework, such as node name, fake system load average, heap usage and disk usage. The number of cores and disk space metrics may be used in autoscaling calculations, so they are tracked and adjusted by SimClusterStateProvider according to the currently active replicas located on each node.

Limitations of the simulation framework

Currently the simulation framework is limited to testing the core autoscaling API in a single JVM. Using it for other purposes would require extensive modifications in Solr and in the framework code. Specifically, the framework supports testing the following autoscaling components: Overseer and CollectionsHandler Cmd implementations are NOT used, so cannot be properly tested - some of their functionality is simulated. Other SolrCloud components make too many direct references to ZkStateReader, or direct HTTP requests, or rely on too many other components and require much more complex functionality - they may be refactored later but the effort may be too high. Simulation framework definitely does not support the following functionality:
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