Terracotta Discussion Forums (LEGACY READ-ONLY ARCHIVE)

Hi guys,

I'm testing offheap storage with bigmemory. I have a simple question, I'm having the following EhCache configuration:

Code:

 <ehcache name="....">    
   <cache name="....."    		 
   		 maxEntriesLocalHeap="1000"
  		 overflowToOffHeap="true" 		 
  		 maxBytesLocalOffHeap="1G"
                  eternal="true"
                  memoryStoreEvictionPolicy="LRU"> 	
  		<persistence strategy="distributed"/>   	          	  	
     	<terracotta/>
   </cache>    
   <terracottaConfig url="localhost:9510"/>
 </ehcache>

In the moment when offheap storage is full, see the attached screenshot Screenshot - 29 I'm seeing log messages like "Data area expansion from....failed"

What does it exactly mean? My guess is that terracotta simply tries to put new entry into the offheapstore, but offheapstore is full. This is the moment when memory eviction policy comes into the play, so terracotta evicts LRU, LFU or FIFO element and puts in the new one?

Please correct me if I'm wrong, thanks a lot in advance

best regards

T.

Hi Tomas,

You're quite correct - what's happening is there isn't enough space to store your key/value pair in the cache currently - and the attempt to allocate space has failed (since the offheap is exhausted). As you guessed this will trigger eviction of other entries in order to store the key/value pair. This logging is at a level that would be below most logging frameworks default thresholds - so you're probably running with more detailed logging switched on. Most people will never see this message, and I would probably recommend you raise your logging thresholds since it's not really very informative and is just going to cause your logs to be overly large.

Chris

Great, thanks a lot for answer.

T.