6.3. Clustered Modes
Red Hat JBoss Data Grid offers the following clustered modes:
- Replication Mode replicates any entry that is added across all cache instances in the cluster.
- Invalidation Mode does not share any data, but signals remote caches to initiate the removal of invalid entries.
- Distribution Mode stores each entry on a subset of nodes instead of on all nodes in the cluster.
The clustered modes can be further configured to use synchronous or asynchronous transport for network communications.
6.3.1. Asynchronous and Synchronous Operations
When a clustered mode (such as invalidation, replication or distribution) is used, data is propagated to other nodes in either a synchronous or asynchronous manner.
If synchronous mode is used, the sender waits for responses from receivers before allowing the thread to continue, whereas asynchronous mode transmits data but does not wait for responses from other nodes in the cluster to continue operations.
Asynchronous mode prioritizes speed over consistency, which is ideal for use cases such as HTTP session replications with sticky sessions enabled. Such a session (or data for other use cases) is always accessed on the same cluster node, unless this node fails.
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6.3.2. Cache Mode Troubleshooting
6.3.2.1. Invalid Data in ReadExternal
If invalid data is passed to
readExternal, it can be because when using Cache.putAsync(), starting serialization can cause your object to be modified, causing the datastream passed to readExternal to be corrupted. This can be resolved if access to the object is synchronized.
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6.3.2.2. About Asynchronous Communications
In Red Hat JBoss Data Grid, the local, distributed and replicated modes are represented by the
local-cache, distributed-cache and replicated-cache elements respectively. Each of these elements contains a mode property, the value of which can be set to SYNC for synchronous or ASYNC for asynchronous communications.
Example 6.1. Asynchronous Communications Example Configuration
<replicated-cache name="default"
start="EAGER"
mode="ASYNC"
batching="false"
statistics="true">
<!-- Additional configuration information here -->
</replicated-cache>Note
This configuration is valid for both JBoss Data Grid's usage modes (Library mode and Remote Client-Server mode).
6.3.2.3. Cluster Physical Address Retrieval
How can the physical addresses of the cluster be retrieved?
The physical address can be retrieved using an instance method call. For example: AdvancedCache.getRpcManager().getTransport().getPhysicalAddresses().
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