18.2.3. Unscheduled Write-Behind Strategy Configuration (Library Mode)

Procedure 18.3. The async Element

1. The modificationQueueSize parameter sets the modification queue size for the asynchronous store. If updates occur faster than the cache store can process the queue, the asynchronous store behaves like a synchronous store. The store behavior remains synchronous and blocks elements until the queue is able to accept them, after which the store behavior becomes asynchronous again.

   <persistence>
       <fileStore location="${LOCATION}">
           <async enabled="true" 
                       modificationQueueSize="1024" />
   

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2. The shutdownTimeout parameter specifies the time in milliseconds after which the cache store is shut down. This provides time for the asynchronous writer to flush data to the store when a cache is shut down. The default value for this parameter is 25000.

   <persistence>
       <fileStore location="${LOCATION}">
           <async enabled="true" 
                       modificationQueueSize="1024" 
                       shutdownTimeout="25000" />
   

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3. The flushLockTimeout parameter specifies the time (in milliseconds) to acquire the lock that guards the state to be periodically flushed. The default value for this parameter is 15000.

   <persistence>
       <fileStore location="${LOCATION}">
           <async enabled="true" 
                       modificationQueueSize="1024" 
                       shutdownTimeout="25000" 
                       flushLockTimeout="15000" />
   

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4. The threadPoolSize parameter specifies the number of threads that concurrently apply modifications to the store. The default value for this parameter is 5.

   <persistence>
       <fileStore location="${LOCATION}">
           <async enabled="true" 
                       modificationQueueSize="1024" 
                       shutdownTimeout="25000" 
                       flushLockTimeout="15000" 
                       threadPoolSize="5"/>
       </fileStore>
   </persistence>
   

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