Question

这是我的Main.java源代码。它是从neo4j-apoc-1.0示例中获取的。修改的目的是存储2个节点和1个关系的1M记录：

package javaapplication2;

import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.graphdb.Transaction;
import org.neo4j.kernel.EmbeddedGraphDatabase;


public class Main
{
    private static final String DB_PATH = "neo4j-store-1M";
    private static final String NAME_KEY = "name";

    private static enum ExampleRelationshipTypes implements RelationshipType
    {
        EXAMPLE
    }

    public static void main(String[] args)
    {
        GraphDatabaseService graphDb = null;

        try
        {
            System.out.println( "Init database..." );


            graphDb = new EmbeddedGraphDatabase( DB_PATH );

            registerShutdownHook( graphDb );


            System.out.println( "Start of creating database..." );


            int valIndex = 0;

            for(int i=0; i<1000; ++i)
            {
                for(int j=0; j<1000; ++j)
                {
                    Transaction tx = graphDb.beginTx();

                    try
                    {
                        Node firstNode = graphDb.createNode();
            firstNode.setProperty( NAME_KEY, "Hello" + valIndex );

                        Node secondNode = graphDb.createNode();
            secondNode.setProperty( NAME_KEY, "World" + valIndex );

                        firstNode.createRelationshipTo(
                           secondNode, ExampleRelationshipTypes.EXAMPLE );

                        tx.success();

                        ++valIndex;
                    }
                    finally
                    {
                        tx.finish();
                    }
                }
            }

            System.out.println("Ok, client processing finished!");
        }
        finally
        {
            System.out.println( "Shutting down database ..." );

            graphDb.shutdown();
        }
    }

    private static void registerShutdownHook( final GraphDatabaseService graphDb )
    {
        // Registers a shutdown hook for the Neo4j instance so that it
        // shuts down nicely when the VM exits (even if you "Ctrl-C" the
        // running example before it's completed)
        Runtime.getRuntime().addShutdownHook( new Thread()
        {
            @Override
            public void run()
            {
                graphDb.shutdown();
            }
        } );
    }
}

经过几次迭代（大约150K）后，我收到错误消息：

“java.lang.OutOfMemoryError：Java堆空间在java.nio.HeapByteBuffer。（HeapByteBuffer.java:39） at java.nio.ByteBuffer.allocate（ByteBuffer.java:312）在org.neo4j.kernel.impl.nioneo.store.PlainPersistenceWindow。（PlainPersistenceWindow.java:30）在org.neo4j.kernel.impl.nioneo.store.PersistenceWindowPool.allocateNewWindow（PersistenceWindowPool.java:534）在org.neo4j.kernel.impl.nioneo.store.PersistenceWindowPool.refreshBricks（PersistenceWindowPool.java:430）在org.neo4j.kernel.impl.nioneo.store.PersistenceWindowPool.acquire（PersistenceWindowPool.java:122）在org.neo4j.kernel.impl.nioneo.store.CommonAbstractStore.acquireWindow（CommonAbstractStore.java:459）在org.neo4j.kernel.impl.nioneo.store.AbstractDynamicStore.updateRecord（AbstractDynamicStore.java:240）在org.neo4j.kernel.impl.nioneo.store.PropertyStore.updateRecord（PropertyStore.java:209）在org.neo4j.kernel.impl.nioneo.xa.Command $ PropertyCommand.execute（Command.java:513）在org.neo4j.kernel.impl.nioneo.xa.NeoTransaction.doCommit（NeoTransaction.java:443）在org.neo4j.kernel.impl.transaction.xaframework.XaTransaction.commit（XaTransaction.java:316） at org.neo4j.kernel.impl.transaction.xaframework.XaResourceManager.commit（XaResourceManager.java:399） at org.neo4j.kernel.impl.transaction.xaframework.XaResourceHelpImpl.commit（XaResourceHelpImpl.java:64）在org.neo4j.kernel.impl.transaction.TransactionImpl.doCommit（TransactionImpl.java:514）在org.neo4j.kernel.impl.transaction.TxManager.commit（TxManager.java:571）在org.neo4j.kernel.impl.transaction.TxManager.commit（TxManager.java:543）在org.neo4j.kernel.impl.transaction.TransactionImpl.commit（TransactionImpl.java:102） at org.neo4j.kernel.EmbeddedGraphDbImpl $ TransactionImpl.finish（EmbeddedGraphDbImpl.java:329）在javaapplication2.Main.main（Main.java:62） 28.05.2010 9:52:14 org.neo4j.kernel.impl.nioneo.store.PersistenceWindowPool logWarn 警告：[neo4j-store-1M \ neostore.propertystore.db.strings]无法分配直接缓冲区“

专家！帮助我plzzz，我做错了什么，我该怎么修呢？在Windows XP 32bit SP3平台上测试。也许在创建自定义配置中的解决方案？

每一条建议都是第4条！

Answer 1

这是Windows上的配置问题，Neo4j无法使用内存映射缓冲区。而是创建堆上的Java缓冲区。在1.0中，此缓冲区默认为470MB，大于Windows JVM的默认堆。您有两种选择：

在pom.xml中切换到APOC 1.1-SNAPSHOT而不是1.0，该pom.xml具有自动配置，将最多50％的可用JVM堆分配给Neo4j
通过使用
运行Java将JVM堆调整为更多（例如512Mb）
java -Xmx512m ....

您甚至可以在Eclipse中的运行配置

如果有帮助，请告诉我们！

此外，为每个节点对执行完整事务将花费很长时间。尝试在第一个循环中打开一个事务，并且只提交每1000个节点对吗？

/彼得

Neo4j OutOfMemory问题

1 个答案: