My requirement is that , i need to group couple of objects together and process
them.
the group size may be small or may be some thousands.
On certain scenarios the objects may be removed from current group and placed
in existing group or new group will get created.
As there is a lot of overhead for jboss cache in handling large key value pairs
under a node, i designed my application in such a way that, I'll populate a
HashMap of key value pairs and put in under cache node with dummy key "0". This
way given me very high performance and persistence speed with JBDM as
persistence store.
When i populate the entire HashMap t oncewith 1000 object and persisted in
cache, the data file size is around 100K. and its perfect.
But when i repeated the population of cache in iteratively i mean gradually,
with the same 1000 objects, the data file is grown to 30MB. how bad.
one step population code is
| public class TestCache {
| private Cache<Long, Object> cache = null;
|
| public TestCache(){
| try {
| CacheFactory<Long, Object> factory = new
DefaultCacheFactory<Long, Object>();
| String cacheConfigFile = "cacheloader.xml";
| cache = factory.createCache(cacheConfigFile);
| cache.create();
| cache.start();
|
| } catch (ConfigurationException e) {
| } catch (CacheException e) {
| }
| }
|
| public void populateCache(){
|
| Map<Long, Object> empMap= new HashMap<Long, Object>();
| for(long i=1; i <= 1000; i++){
| Employee emp = new Employee(i,"Test name "+i,"test
region "+i);
| empMap.put(i, emp);
| }
|
| Node<Long, Object> collNode =
cache.getRoot().addChild(Fqn.fromElements("test","emp","cache"));
| collNode.put(0L, empMap);
| cache.stop();
|
| }
| public static void main(String[] args) {
| TestCache tc= new TestCache();
| tc.populateCache();
|
| }
| }
|
the second program which kept iteratively is
| public class TestCache {
| private Cache<Long, Object> cache = null;
|
| public TestCache(){
| try {
| CacheFactory<Long, Object> factory = new
DefaultCacheFactory<Long, Object>();
| String cacheConfigFile = "cacheloader.xml";
| cache = factory.createCache(cacheConfigFile);
| cache.create();
| cache.start();
| } catch (ConfigurationException e) {
| } catch (CacheException e) {
| }
| }
|
| public void populateCache(){
| Map<Long, Object> empMap= null;
| for(long i=1; i <= 1000; i++){
| Employee emp = new Employee(i,"Test name "+i,"test
region "+i);
| Node<Long, Object> collNode =
cache.getRoot().getChild(Fqn.fromElements("test","emp","cache"));
|
| if(collNode == null){
| collNode =
cache.getRoot().addChild(Fqn.fromElements("test","emp","cache"));
| }
|
| empMap = (Map<Long, Object>)collNode.get(0L);
| if(empMap == null)
| empMap= new HashMap<Long, Object>();
|
| empMap.put(i, emp);
| collNode.clearData();
| collNode.remove(0L);
| collNode.put(0L, empMap);
| }
|
| cache.stop();
| }
|
| public static void main(String[] args) {
| TestCache tc= new TestCache();
| tc.populateCache();
|
| }
|
| }
|
|
configuration file is
| <?xml version="1.0" encoding="UTF-8"?>
| <jbosscache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
| xmlns="urn:jboss:jbosscache-core:config:3.0">
|
| <transaction
|
transactionManagerLookupClass="org.jboss.cache.transaction.GenericTransactionManagerLookup"
/>
| <locking
| isolationLevel="REPEATABLE_READ"
| lockParentForChildInsertRemove="false"
| lockAcquisitionTimeout="20000"
| nodeLockingScheme="mvcc"
| writeSkewCheck="false"
| concurrencyLevel="500"/>
| <invocationBatching enabled="true"/>
| <jmxStatistics enabled="true"/>
| <loaders passivation="false" shared="false">
| <preload>
| <node fqn="/" />
| </preload>
| <loader class ="org.jboss.cache.loader.jdbm.JdbmCacheLoader"
| async="false" fetchPersistentState="true"
ignoreModifications="false" >
| <properties>
| location=/home/sridhar/cache
|
cache.jdbc.connection.factory=org.jboss.cache.loader.C3p0ConnectionFactory
| c3p0.maxPoolSize=10
| c3p0.checkoutTimeout=5000
| </properties>
| </loader>
| </loaders>
| </jbosscache>
|
|
in the second program when i replaced the HashMap with Set, there is no
difference in the size of data files created.
Why such strange behaviour. what will be the solution to this?
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