Kryo 序列化导致自定义对象的致命 Java 运行时错误

Question

我正在尝试序列化两个自定义类的哈希图和集合（包含更多哈希图和集合）。

Class1：NodeStorage.java

@NotNull
private final String id;

@Nullable
private String type;

@Nullable
private HashMap<String, String> properties;

Class2：RelationshipStorage.java

    @NotNull
private final String id;

@Nullable
private String type;

@Nullable
private HashMap<String, String> properties;

@NotNull
private final NodeStorage startNode;

@NotNull
private final NodeStorage endNode;

要序列化的集合：

private HashMap<NodeStorage, NodeStorage> readsSetNode;
private HashMap<NodeStorage, NodeStorage> updateSetNode;
private ArrayList<NodeStorage>            deleteSetNode;
private ArrayList<NodeStorage>            createSetNode;

private HashMap<RelationshipStorage, RelationshipStorage> readsSetRelationship;
private HashMap<RelationshipStorage, RelationshipStorage> updateSetRelationship;
private ArrayList<RelationshipStorage>                    deleteSetRelationship;
private ArrayList<RelationshipStorage>                    createSetRelationship;

我到现在为止的尝试：

 kryo.register(NodeStorage.class, 1);
    kryo.register(RelationshipStorage.class, 2);
    kryo.register(HashMap.class, mapSerializer);

    mapSerializer.setKeyClass(NodeStorage.class, kryo.getSerializer(NodeStorage.class));
    mapSerializer.setKeyClass(RelationshipStorage.class, kryo.getSerializer(RelationshipStorage.class));
    mapSerializer.setValuesCanBeNull(false);
    mapSerializer.setKeysCanBeNull(false);
    listSerializer.setElementClass(NodeStorage.class, kryo.getSerializer(NodeStorage.class));
    listSerializer.setElementClass(RelationshipStorage.class, kryo.getSerializer(RelationshipStorage.class));
    listSerializer.setElementsCanBeNull(false);


    public byte[] serialize()
{
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    Output output = new Output(stream);
    mapSerializer.write(kryo, output, readsSetNode);
    byte[] bytes = output.toBytes();
    output.close();
    return bytes;
}

我用 kryo.writeclassandobject 尝试过，但效果不佳。我明白了：

> > #
> # A fatal error has been detected by the Java Runtime Environment:
> #
> #  SIGSEGV (0xb) at pc=0x00007f92f7f6efe0, pid=4637, tid=0x00007f92f94fd700
> #
> # JRE version: OpenJDK Runtime Environment (8.0_102-b14) (build 1.8.0_102-b14)
> # Java VM: OpenJDK 64-Bit Server VM (25.102-b14 mixed mode linux-amd64 compressed oops)
> # Problematic frame:
> # V  [libjvm.so+0x787fe0]
> #
> # Core dump written

完整代码在：https://github.com/Raycoms/thesis

声明：

private Kryo kryo = new Kryo();
MapSerializer        mapSerializer  = new MapSerializer();
CollectionSerializer listSerializer = new CollectionSerializer();

Answer 1

Kryo 不是线程安全的，实际上任何 Java 程序都有多个线程在运行。例如，您的log file 表明您在崩溃时有 25 个线程在运行。即使您的 Kryo 实例是私有的，但错误在 Kryo 的内部深处，并且可能存在不受您控制的线程或 JVM 交互。

尝试下面引用的线程池方法，详细信息在Kryo readme：

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.pool.*;

KryoFactory factory = new KryoFactory() {
  public Kryo create () {
    Kryo kryo = new Kryo();
    // configure kryo instance, customize settings
    return kryo;
  }
};
// Build pool with SoftReferences enabled (optional)
KryoPool pool = new KryoPool.Builder(factory).softReferences().build();

然后，在您的 serialize() 函数中：

Kryo kryo = pool.borrow();
<... the rest of your code in serialize() before the return...>
pool.release(kryo);
return bytes;

正如自述文件指出的那样，您也可以使用回调：

// or use a callback to work with kryo - no need to borrow/release,
// that's done by `run`.
String value = pool.run(new KryoCallback() {
  public String execute(Kryo kryo) {
    return kryo.readObject(input, String.class);
  }
});

OP的最终代码

从 OP 的评论中发布到这里，以便其他人可以更轻松地阅读它。 OP 最终无法使用mapSerializer，但能够使用此代码进行序列化：

private byte[] serialize() { 
    KryoPool pool = new KryoPool.Builder(factory).softReferences().build();
    Kryo kryo = pool.borrow();
    Output output = new Output(0, 1024);
    kryo.writeClassAndObject(output, readsSetNode);
    byte[] bytes = output.toBytes();
    output.close();
    pool.release(kryo);
    return bytes;
}

注意正如@MartinGrotzke 指出的那样，根据this issue，如果您使用kryo.register(class, id)，请确保id>=10。