<commit_before># Release Notes

## 2.7.3

### Compatibility

In order to unify the implementation of service governance rules in different configuration centers, such as Zookeeper, Nacos, Etcd, etc., we have refactored some implementations of the configuration center compared to 2.7.0~2.7.2.

* For users who are using 2.7.x service governance rules, please check [the new implementation](http://dubbo.apache.org/en-us/docs/dev/impls/Config-center.html) before upgrading to 2.7.3, make sure all rules have a copy under the new storage path to ensure a smooth upgrade. 
* For users who have upgraded the 2.7.x version but are not using any service governance rules, you can upgrade directly. 
* For users using 2.6.x and lower versions can upgrade directly. But make sure you follow the following instructions [Upgrading from 2.6.x to 2.7.x](https://github.com/apache/dubbo/releases/tag/dubbo-2.7.0)

### Change List

1. Asynchronous support

    - Unified asynchronous and synchronous callback process, exception scenario triggers onError callback, #4401.
    - Performance degradation caused by CompletableFuture.get() in JDK1.8 environment, #4279.

2. Configuration Center

    - ConfigCenter custom namespace does not take effect, #4411.
    - Unify the models implemented by several configuration centers such as Zookeeper, Nacos, and Etcd. Please refer to the description for possible incompatibility issues, #4388.
    - Adjust Override Coverage Rule Center Priority: Service Level > Application Level, #4175.

3. 2.6.x compatibility

    - Support Zipkin tracing feature provided by Zipkin officially, #3728, #4471.
    - DubboComponentScan supports simultaneous scanning of annotations under the `com.alibaba.*` and `org.apache.*` packages, #4330.

4. The Nacos Registration Center only subscribes to the address list and no longer subscribes to configuration information, #4454.

5. Support to read the environment configuration from the specified location, which can be specified by -D or OS VARIABLE. Please refer to [automatically loading environment variables](http://dubbo.apache.org/en-us/docs/user/configuration/environment-variables.html)

6. Some other bugfixes, #4346 #4338 #4349 #4377

### 升级注意事项

为了统一不同配置中心（如Zookeeper、Nacos、Etcd等）对于服务治理规则的实现，我们对2.7.0以来的配置中心的部分实现进行了重构。

* 对于已使用了2.7.x新版本服务治理规则的用户，升级2.7.3之前请先[查看新版实现](http://dubbo.apache.org/zh-cn/docs/dev/impls/config-center.html)，确保已有规则在新路径下已经存在拷贝，以确保平滑升级。
* 对于已经升级了2.7.x版本，但是未使用服务治理规则的用户，此次升级不受影响。
* 对于2.6.x及以下版本用户不受此次变更影响，升级步骤请参见[升级到2.7.x的说明文档](https://github.com/apache/dubbo/releases/tag/dubbo-2.7.0)。

### Change List

1. 异步支持相关

    - 统一异步和同步的回调流程，异常场景触发onError回调 #4401
    - CompletableFuture.get()在JDK1.8环境下带来的性能下降问题 #4279<commit_msg>polish 2.7.3 change list<commit_after># Release Notes

## 2.7.3

### Change List

1. Asynchronous support

    - Unified asynchronous and synchronous callback process, exception scenario triggers onError callback, #4401.
    - Performance degradation caused by CompletableFuture.get() in JDK1.8 environment, #4279.

2. Configuration Center

    - ConfigCenter custom namespace does not take effect, #4411.
    - Unify the models implemented by several configuration centers such as Zookeeper, Nacos, and Etcd. Please refer to the description for possible incompatibility issues, #4388.
    - Adjust Override Coverage Rule Center Priority: Service Level > Application Level, #4175.

3. 2.6.x compatibility

    - Support Zipkin tracing feature provided by Zipkin officially, #3728, #4471.
    - DubboComponentScan supports simultaneous scanning of annotations under the `com.alibaba.*` and `org.apache.*` packages, #4330.

4. The Nacos Registration Center only subscribes to the address list and no longer subscribes to configuration information, #4454.

5. Support to read the environment configuration from the specified location, which can be specified by -D or OS VARIABLE. Please refer to [automatically loading environment variables](http://dubbo.apache.org/en-us/docs/user/configuration/environment-variables.html)

6. Some other bugfixes, #4346 #4338 #4349 #4377

### Change List

1. 异步支持相关

    - 统一异步和同步的回调流程，异常场景触发onError回调 #4401
    - CompletableFuture.get()在JDK1.8环境下带来的性能下降问题 #4279
{'fraction_non_alphanumeric': 0.08479809976247031, 'fraction_numerical': 0.04608076009501188, 'mean_word_length': 4.461738002594034, 'pattern_counts': {'":': 0, '<': 3, '<?xml version=': 0, '>': 5, 'https://': 2, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
{'dir': 'git-commits-cleaned', 'id': '4682299', 'n_tokens_mistral': 1569, 'n_tokens_neox': 1484, 'n_words': 446}