7.6. Configure Distribution Mode (Library Mode)

Procedure 7.2. Distributed Cache Configuration

1. Set the Clustered Mode

   The clustering element's mode parameter's value determines the clustering mode selected for the cache.

   <clustering mode="distribution">

2. Specify the Remote Call Timeout

   The sync element's replTimeout parameter specifies the maximum time period in milliseconds for an acknowledgment after a remote call. If the time period ends without any acknowledgment, an exception is thrown.

   <clustering mode="distribution">
           <sync replTimeout="${TIME}" />

3. Define State Transfer Settings

   The stateTransfer element specifies how state is transferred when a node leaves or joins the cluster. It uses the following parameters:

   1. Specify State Transfer Batch Size

      The chunkSize parameter is the number of cache entries to be transferred in one chunk. The default chunkSize value is 512. The chunkSize depends on many parameters (for example, size of entries) and the best setting needs to be measured. To change the value for larger cache entries, smaller chunks are advisable and for smaller cache entries, increasing the chunkSize offers better performance.

      <clustering mode="distribution">
              <sync replTimeout="${TIME}" />
              <stateTransfer chunkSize="${SIZE}" />

   2. Set fetchInMemoryState Parameter

      The fetchInMemoryState parameter when set to true, requests state information from neighboring caches on start up. This impacts the start up time for the cache.

      <clustering mode="distribution">
              <sync replTimeout="${TIME}" />
              <stateTransfer chunkSize="${SIZE}"
                             fetchInMemoryState="{true/false}" />

   3. Define the awaitInitialTransfer Parameter

      The awaitInitialTransfer parameter causes the first call to method CacheManager.getCache() on the joiner node to block and wait until the joining is complete and the cache has finished receiving state from neighboring caches (if fetchInMemoryState is enabled). This option applies to distributed and replicated caches only and is enabled by default.

      <clustering mode="distribution">
              <sync replTimeout="${TIME}" />
              <stateTransfer chunkSize="${SIZE}"
                             fetchInMemoryState="{true/false}"
                             awaitInitialTransfer="{true/false}" />

   4. Set timeout Value

      The timeout parameter specifies the maximum time (in milliseconds) the cache waits for responses from neighboring caches with the requested states. If no response is received within the the timeout period, the start up process aborts and an exception is thrown.

      <clustering mode="distribution">
              <sync replTimeout="${TIME}" />
              <stateTransfer chunkSize="${SIZE}"
                             fetchInMemoryState="{true/false}"
                             awaitInitialTransfer="{true/false}"
                             timeout="${TIME}" />

4. Specify Transport Configuration

   The transport element defines the transport configuration for the cache container as follows:

   1. Specify the Cluster Name

      The clusterName parameter specifies the name of the cluster. Nodes can only connect to clusters that share the same name.

      <global>
          <transport clusterName="${NAME}" />
      </global>

   2. Set the distributedSyncTimeout Value

      The distributedSyncTimeout parameter specifies the time to wait to acquire a lock on the distributed lock. This distributed lock ensures that a single cache can transfer state or rehash state at a time.

      <global>
          <transport clusterName="${NAME}"
              distributedSyncTimeout="${TIME}" />
      </global>

   3. Set the Network Transport

      The transportClass parameter specifies a class that represents a network transport for the cache container.

      <global>
          <transport clusterName="${NAME}"
              distributedSyncTimeout="${TIME}"
              transportClass="${CLASS}" />
      </global>