JSON Streaming write and NUL characters or 0x00 writes for random objects

[vkumart]

Hi,
We are facing this intermittent issue where on a multi-object serialization(pretty large - Think of this as say a database serialization to JSON), at random places and for random objects the file contains NUL(0x00) for some writes. the content before and after are fine.

Please note that this is highly intermittent and we are not able to root cause the issue. Following are more details

• We are using Kotlin with JDK 17.0 and Kotlin

 <jackson.version>2.18.2</jackson.version>
 <kotlin.version>1.9.22</kotlin.version>

• We are using Jackson streaming as follows

val mapper = new jacksonObjectMapper()
            .registerModule(ParameterNamesModule())
            .registerModule(JavaTimeModule())
            .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
            .setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.NON_PRIVATE)
            .setVisibility(PropertyAccessor.CREATOR, JsonAutoDetect.Visibility.ANY)
 val file = new File("test.json")
 val generator = objectMapper.factory.createGenerator(file.outputStream())
// all the entities, we call
 generator.writeObject(entity) // These entities are Kotlin data classes.

We do have a parallel write use case where multiple threads write to same json generator - by synchronized at the writing function level.

Questions

1. Is the access pattern correct?
2. Is there any known issues of random NUL writes happening?
3. Concurrent writes are supported? If not @synchronized should serialize writes, I supopose.