A very simple solution for a queryWithRowHandler when fails due to
OutOfMemoryError
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Key: IBATIS-474
URL: https://issues.apache.org/jira/browse/IBATIS-474
Project: iBatis for Java
Issue Type: Wish
Components: DAO
Reporter: haruhiko nishi
Priority: Trivial
A simple solution to queryWithRowHandler gets OutOfMemoryError when it needs
to process very large results. Works only if the primary key of the target
table is numeric sequence.
public void queryWithRowHandler(String id,NumericRange numericRange,RowHandler
rowHandler,boolean continueWithError){
DaoException exception=null;
boolean retryOccured=false;
int retryCount=retry_count;
int retryInterval=retry_interval;
for(;;){
do{
if(retryOccured||numericRange.hasNextRange()){
try{
daoManager.startTransaction();
super.queryWithRowHandler(id,numericRange,rowHandler);
daoManager.commitTransaction();
if(retryOccured){
retryOccured=!retryOccured;
retryCount=retry_count;
}
}catch(DaoException e){
exception=e;
retryOccured=true;
try{
Thread.sleep(retryInterval * 1000);
}catch(InterruptedException ignored){}
}finally{
daoManager.endTransaction();
}
}else
return;
}while(retryOccured && (--retryCount>0));
if(retryCount==0){
retryOccured=false;
retryCount=retry_count;
if(!continueWithError)
throw exception;
}
}
}
public class NumericRange {
private final ReentrantLock mainLock = new ReentrantLock();
private int range;
private volatile int max;
private volatile int min;
private AtomicInteger nextMax;
public NumericRange(int range,int max){
if(range<0||max<0)
throw new IllegalArgumentException();
this.range=range;
this.nextMax=new AtomicInteger(max);
}
protected final boolean hasNextRange(){
int n,tmpMax;
mainLock.lock();
try{
max=nextMax.get();
if((n=max - range -1)> 0)
nextMax.set(n);
else
nextMax.set(0);
min=Math.max(0,max-range);
return max>0;
}finally{
mainLock.unlock();
}
}
public int getMin(){
return this.min;
}
public int getMax(){
return this.max;
}
}
<select id="queryWithRowHandler" resultClass="member"
parameterClass="NumericRange">
SELECT *
FROM TABLE WHERE primary_key BETWEEN #min# and #max#
</select>
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