balodesecurity opened a new pull request, #8291:
URL: https://github.com/apache/hadoop/pull/8291
## Problem
When `DataNode.refreshNamenodes()` is called to add a new nameservice it
reloads configuration via `setConf(new Configuration())`, but
`DatanodeHttpServer` kept holding a stale reference to the old `Configuration`.
Subsequent WebHDFS requests for blocks on the newly-added nameservice would
fail because the `DFSClient` created per-request could not resolve the namenode
addresses for that nameservice from the stale config.
Root cause: `DatanodeHttpServer.conf` and `confForCreate` were `final`
fields set once at construction time. `DataNode.refreshNamenodes()` never
called any update method on `httpServer`.
## Fix
- Make `conf` and `confForCreate` in `DatanodeHttpServer` `volatile`
(non-final) so Netty I/O threads see updates atomically.
- Add `DatanodeHttpServer.updateConf(Configuration newConf)` that refreshes
both fields and the embedded Jetty `infoServer`'s servlet-context attributes
(`CONF_CONTEXT_ATTRIBUTE`, `CURRENT_CONF`).
- Call `httpServer.updateConf(getConf())` at the end of
`DataNode.refreshNamenodes()` after the new configuration has been loaded.
The Netty `ChannelInitializer` creates a fresh `URLDispatcher` per
connection and reads `DatanodeHttpServer.conf` at that point, so new
connections automatically pick up the updated configuration without requiring a
pipeline or server restart.
## Testing
- Added `TestDatanodeHttpServerUpdateConf.testUpdateConfRefreshesFields` — a
unit test (no cluster required) that:
- Creates a `DatanodeHttpServer` with an initial configuration.
- Calls `updateConf(newConf)`.
- Asserts (via reflection) that the `conf` and `confForCreate` instance
fields now reference the updated configuration.
- Asserts that the Jetty `infoServer` servlet-context attributes have been
updated.
```
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
```
## Related
- JIRA: https://issues.apache.org/jira/browse/HDFS-16842
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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