Static use of Dozer Mapper

Question

Just wondering if having a static dozer mapper like this can leads to concurrency errors :

public static Mapper mapper = new DozerBeanMapper();
public static MyDTO toDTO(MyEntity e) {
    MyDTO dto = mapper.map(e, MyDTO.class);
    return dto;
}

Or should I always use this code :

public static MyDTO toDTO(MyEntity e) {
    Mapper mapper = new DozerBeanMapper();
    MyDTO dto = mapper.map(e, MyDTO.class);
    return dto;
}

The method is used in an @Stateless session bean of a JBoss Server, it can be accessed concurrently. The fact is I dont really know if Dozer makes use of static variables or instance variables in the library to decide if I can/should use a static Mapper or create a new instance at every call.

Answer 1

Dozer instance could be static. If you would create new instance for each request the performance will be much worse, since lots of the caches will be initialised every time. ConcurrencyErrors may be encountered either due to bugs in Custom Converters or internal Dozer problems.