Java Neo4J 内存不足

Question

这有点像这样:Neo4j OutOfMemory problem

但它已经过时，据我所知，解决方案显然也是如此。

所以我尝试插入大约 10 万个节点和 550 万个关系(我实际上缩减了我的数据集，所以它现在更像是 <10 万个节点和 280 万个关系)。

一段时间后，内存不足，我得到如下异常:

Exception in thread "GC-Monitor" java.lang.OutOfMemoryError: Java heap space
    at java.util.Arrays.copyOfRange(Unknown Source)
    at java.lang.String.<init>(Unknown Source)
    at java.lang.StringBuilder.toString(Unknown Source)
    at org.neo4j.kernel.impl.util.StringLogger$ActualStringLogger.logMessage(StringLogger.java:276)
    at org.neo4j.kernel.impl.cache.MeasureDoNothing.run(MeasureDoNothing.java:85)
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.LinkedList.addBefore(Unknown Source)
    at java.util.LinkedList.add(Unknown Source)
    at org.neo4j.kernel.impl.nioneo.store.IdGeneratorImpl.freeId(IdGeneratorImpl.java:291)
    at org.neo4j.kernel.impl.nioneo.store.CommonAbstractStore.freeId(CommonAbstractStore.java:382)
    at org.neo4j.kernel.impl.nioneo.xa.WriteTransaction.doRollback(WriteTransaction.java:315)
    at org.neo4j.kernel.impl.transaction.xaframework.XaTransaction.rollback(XaTransaction.java:278)
    at org.neo4j.kernel.impl.transaction.xaframework.XaResourceManager.rollback(XaResourceManager.java:518)
    at org.neo4j.kernel.impl.transaction.xaframework.XaResourceHelpImpl.rollback(XaResourceHelpImpl.java:111)
    at org.neo4j.kernel.impl.transaction.TransactionImpl.doRollback(TransactionImpl.java:558)
    at org.neo4j.kernel.impl.transaction.TxManager.rollback(TxManager.java:610)
    at org.neo4j.kernel.impl.transaction.TransactionImpl.rollback(TransactionImpl.java:129)
    at org.neo4j.kernel.TopLevelTransaction.finish(TopLevelTransaction.java:119)
    at sqlToGraph.SqlToGraph.main(SqlToGraph.java:81)

我已经尝试将 -Xmx1500m 传递给 java，这大约是我可以传递的限制，因为在它提示无法分配堆空间之前。它持续的时间明显更长，但仍未结束。

这是(略有编辑的)代码:

/* Postgres query and setup stuff cut */
Transaction tx = graphDb.beginTx();
try {
    while (rs.next()) {
        user_lo = rs.getInt(1);
        user_hi = rs.getInt(2);
        n_lo = getOrCreate(user_lo, graphDb);
        n_lo.setProperty("user_id", user_lo);
        n_lo.setProperty("total", rs.getInt(3));
        n_hi = getOrCreate(user_hi, graphDb);
        n_hi.setProperty("user_id", user_hi);
        n_hi.setProperty("total", rs.getInt(4));
        relationship = n_lo.createRelationshipTo(n_hi, RelTypes.PLAYED_WITH);
        relationship.setProperty("mean_percent", rs.getDouble(5));
    }
    tx.success();
} finally {
    tx.finish();
}
graphDb.shutdown();

Answer 1

在这里添加另一个答案。所以给定代码，问题是你永远不会提交你的事务。事务数据在提交之前一直保存在内存中，因此您创建的所有节点和关系都将保存在内存中等待提交，这就是您最终会出现 OOM 的原因。

我建议更改此代码:

/* Postgres query and setup stuff cut */Transaction tx = graphDb.beginTx();try {    for (int i = 0; rs.next(); i++) {        user_lo = rs.getInt(1);        user_hi = rs.getInt(2);        n_lo = getOrCreate(user_lo, graphDb);        n_lo.setProperty("user_id", user_lo);        n_lo.setProperty("total", rs.getInt(3));        n_hi = getOrCreate(user_hi, graphDb);        n_hi.setProperty("user_id", user_hi);        n_hi.setProperty("total", rs.getInt(4));        relationship = n_lo.createRelationshipTo(n_hi, RelTypes.PLAYED_WITH);        relationship.setProperty("mean_percent", rs.getDouble(5));        // Commit every now and then to free memory.        if ( i > 0 && i % 10000 == 0 ) {            tx.success();            tx.finish();            tx = graphDb.beginTx();        }    }    tx.success();} finally {    tx.finish();}graphDb.shutdown();