问题
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 -
- Thread 1 enters CustomerSerializer and starts to serialize
- Thread 2 enters CustomSerializer, interuptting Thread 1, and starts to serialize from start to finish
- Thread 1 resumes, and the last thing being serialized is missing
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?
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);
}
And an example of where it is used
SimpleModule sm = new SimpleModule();
sm.addSerializer(new myCustomSerializer());
new ObjectMapper().registerModule(sm)
.writeValue(new myObject());
回答1:
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.
来源：https://stackoverflow.com/questions/20956385/jackson-objectmapper-jsongenerator-is-it-thread-safe