当调用ElasticsearchClient的query方法时, static字段丢失或者改变, 这是为什么呀

Elastic In Your Native Tongue 中文提问与讨论
1

Java API client version: 7.17.10
Java version: jdk-17.0.3.1
Elasticsearch Version: 7.17

我有个代码仓库可以复现这个问题: GitHub - xiaochunyong/elasticsearch-threadlocal-reference-changed

有一个类UserHolder, 里面有个ThreadLocal变量

public class UserHolder {

    public static ThreadLocal<String> holder = new ThreadLocal<>();

}

当在PostController中调用ElasticsearchClient.query方法时, 进入query方法前和进入方法后, currentThread不一样

@RestController
@RequestMapping("/api/post")
public class PostController {

    @Autowired
    private ElasticsearchClient client;

    public static Thread currentThread;

    public static String welcome = "hello1";

    @GetMapping
    public Object query() throws IOException {
        currentThread = Thread.currentThread();
        welcome = "hello2";

        SearchResponse<ObjectNode> search = client.search(s -> s
                        .index("post")
                        .query(b -> b
                                .matchAll(b2 -> b2)
                        ),
                ObjectNode.class
        );

        return search.hits().hits();
    }

}

Outside the query method
Outside the query method2490×1514 386 KB

2

inside the query method
inside the query method2468×1600 434 KB

3

I found the reason. I used spring-boot-devtools. The class loader used by the class under src is different from the class loader in the jar package.