[JAVA] DB programming using EclipseLink part1

At the beginning

I tried DB programming using EclipseLink because it seems to be necessary for business

Sample program

I wrote a program to insert the serial number of 1 into the DB

InsertLogic.java

package logic;

import java.util.Date;
import java.util.stream.Stream;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

import entiry.SequeceNum;


public class InsertLogic {
	public static void main(String args[]){
		new InsertLogic().doLogic();
	}

	public void doLogic(){
		EntityManagerFactory factory = Persistence.createEntityManagerFactory("myUnitInPersistenceXML");
		EntityManager em = factory.createEntityManager();
		long start =System.currentTimeMillis();
		System.out.println("insert start");
		em.getTransaction().begin();
		
    	Stream.iterate(1l, s->s+1)
    	.limit(1000000000000l)
    	.map(i->createSequeceNum(i))
    	.forEach(o->doInsert(em,o));
		System.out.println("insert End");
		long ends =System.currentTimeMillis();
		System.out.println(String.format("Time taken%d", (ends - start)));
    	
	}
	
	private static SequeceNum createSequeceNum(long i){
		SequeceNum myEntity = new SequeceNum();
		myEntity.setId(i);
		return myEntity;
	}
	private static void doInsert(EntityManager em,SequeceNum entity){
		em.persist(entity);
		if(entity.getId()%100000 == 0){
			em.getTransaction().commit();
			em.getTransaction().begin();
		}
	}
}

SequeceNum.java

package entiry;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class SequeceNum {
	@Id
	private long id;

	public long getId() {
		return id;
	}

	public void setId(long id) {
		this.id = id;
	}
}

If you execute it as it is, the following error will appear

[EL Info]: 2017-12-03 21:56:37.505--ServerSession(336400944)--EclipseLink, version: Eclipse Persistence Services - 2.5.1.v20130918-f2b9fc5
[EL Info]: connection: 2017-12-03 21:56:38.156--ServerSession(336400944)--file:/C:/Users/takayoshi/workspace/Pazzle/bin/_myUnitInPersistenceXML login successful
insert start
Exception in thread "main" java.lang.OutOfMemoryError: GC overhead limit exceeded
	at org.eclipse.persistence.internal.descriptors.ObjectBuilder.createObjectChangeSet(ObjectBuilder.java:2872)
	at org.eclipse.persistence.descriptors.changetracking.DeferredChangeDetectionPolicy.createObjectChangeSetThroughComparison(DeferredChangeDetectionPolicy.java:155)
	at org.eclipse.persistence.descriptors.changetracking.DeferredChangeDetectionPolicy.createObjectChangeSet(DeferredChangeDetectionPolicy.java:146)
	at org.eclipse.persistence.descriptors.changetracking.DeferredChangeDetectionPolicy.calculateChanges(DeferredChangeDetectionPolicy.java:91)
	at org.eclipse.persistence.descriptors.changetracking.DeferredChangeDetectionPolicy.calculateChangesForExistingObject(DeferredChangeDetectionPolicy.java:56)
	at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.calculateChanges(UnitOfWorkImpl.java:664)
	at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitToDatabaseWithChangeSet(UnitOfWorkImpl.java:1516)
	at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.commitRootUnitOfWork(RepeatableWriteUnitOfWork.java:277)
	at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitAndResume(UnitOfWorkImpl.java:1169)
	at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commit(EntityTransactionImpl.java:132)
	at logic.InsertLogic.doInsert(InsertLogic.java:43)
	at logic.InsertLogic.lambda$2(InsertLogic.java:28)
	at logic.InsertLogic$$Lambda$6/2137034273.accept(Unknown Source)
	at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(Unknown Source)
	at java.util.stream.ReferencePipeline$3$1.accept(Unknown Source)
	at java.util.stream.SliceOps$1$1.accept(Unknown Source)
	at java.util.Spliterators$IteratorSpliterator.tryAdvance(Unknown Source)
	at java.util.stream.ReferencePipeline.forEachWithCancel(Unknown Source)
	at java.util.stream.AbstractPipeline.copyIntoWithCancel(Unknown Source)
	at java.util.stream.AbstractPipeline.copyInto(Unknown Source)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
	at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(Unknown Source)
	at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(Unknown Source)
	at java.util.stream.AbstractPipeline.evaluate(Unknown Source)
	at java.util.stream.ReferencePipeline.forEach(Unknown Source)
	at logic.InsertLogic.doLogic(InsertLogic.java:28)
	at logic.InsertLogic.main(InsertLogic.java:15)
[EL Info]: connection: 2017-12-03 22:23:39.469--ServerSession(336400944)--file:/C:/Users/takayoshi/workspace/Pazzle/bin/_myUnitInPersistenceXML logout successful

Apparently, the result of executing in memory seems to remain in the cache, and the heap area seems to be exhausted. By the way, the number of rows inserted into the DB when the heap is exhausted is as follows.

  COUNT(*)
----------
   2400001

Apparently, if you execute the Insert statement without any ingenuity, an error will occur in about 250,000 even with a simple data structure. I will write an improvement plan in the next entry