杰克逊对象映射器JsonGenerator-线程安全吗? [英] Jackson ObjectMapper & JsonGenerator - is it thread-safe?

问题描述

我目前有一个项目，该项目使用杰克逊更快的xml通过自定义序列化器和反序列化器将POJO序列化/反序列化到Json.据我了解，一旦创建并配置了ObjectMapper，它就是线程安全的.但是，我注意到在使用JMeter运行测试时，偶尔会发生以下情况-

I currently have a project which uses jackson faster xml to serialize/deserialize POJOs to Json using custom serializers and deserializers. From what I understand, the ObjectMapper is thread-safe once it has been created and configured. However, I have noticed when running tests with JMeter that occasionally the following can happen -

• 线程1进入CustomerSerializer并开始序列化
• 线程2进入CustomSerializer，并与线程1交互，并开始从头到尾进行序列化
• 线程1恢复，并且最后一个序列化的内容丢失了

似乎是在第二个线程进入时重置了JsonGenerator实例-肯定不应该发生这种情况吗?我检查了几个站点和线程，以查看是否需要设置任何设置或功能，但是据我了解，ObjectMapper重用了JsonGenerator实例，这可能是问题吗?

It seems to be that the JsonGenerator instance is being reset when the second thread has entered - surely this shouldn't be happening? I have checked several sites and threads to see if there are any settings or features I need to set, but from what I understand the ObjectMapper reuses JsonGenerator instances, could this be the issue?

以下是我的自定义序列化器中的代码段...

The following is a snippet from my custom serializer...

@Override
public final void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {

    jsonGenerator.writeStartObject();

    ... Code here ....

    jsonGenerator.writeEndObject();

    closeJsonGenerator(jsonGenerator);
}

以及使用位置的示例

SimpleModule sm = new SimpleModule();
sm.addSerializer(new myCustomSerializer());
new ObjectMapper().registerModule(sm)
                  .writeValue(new myObject());

推荐答案

Jackson的ObjectMapper在每个序列化请求上创建一个新的JsonGenerator.从这个意义上讲，可以保证它是线程安全的.我可以看到的唯一可能导致您看到的行为的情况是，您的CustomSerializer是否具有正在共享的某些实例字段并且正在执行某种内部同步.

Jackson's ObjectMapper creates a new JsonGenerator on each request for serialization. In that sense, it is guaranteed to be thread safe. The only thing that I can see that might cause the behavior you are seeing is if your CustomSerializer has some instance fields that it is sharing and is doing some kind of internal synchronization.

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