hiwuya opened a new pull request, #10861:
URL: https://github.com/apache/ozone/pull/10861
## What changes were proposed in this pull request?
This PR fixes a `NullPointerException` during EC degraded reads when the
Ozone client runs inside an isolated plugin class loader (e.g. Trino Hive
connector).
Normal reads succeed, but when a DataNode is unavailable, the EC degraded
read path fails with:
```
java.lang.NullPointerException:
Cannot read the array length because "<local3>" is null
at org.apache.ozone.erasurecode.rawcoder.util.CodecUtil
.createRawDecoderWithFallback(CodecUtil.java:90)
```
Root cause: `CodecRegistry` loads coder factories via
`ServiceLoader.load(RawErasureCoderFactory.class)`, which uses the **thread
context class loader (TCCL)**. In Trino's isolated plugin class loader, the
TCCL cannot see the Ozone `META-INF/services` providers, so
`getCoderNames("rs")` returns `null`, causing the NPE in `CodecUtil`. Spark
works because its TCCL can see the Ozone providers.
**Fix:** Use `CodecRegistry`'s own class loader instead of the TCCL:
```java
ServiceLoader.load(RawErasureCoderFactory.class,
CodecRegistry.class.getClassLoader());
```
No changes to the singleton pattern, registration logic, native coder
priority, fallback order, or public API.
## What is the link to the Apache JIRA
https://issues.apache.org/jira/browse/HDDS-15963
## How was this patch tested?
- Added `testRegistryLoadsWithoutTccl`: sets TCCL to an empty
`ClassLoader(null)` before first `CodecRegistry` initialization, then verifies
`getCoderNames("rs")` is non-null, non-empty, and contains `rs_java`. Restores
TCCL in `finally`.
- Confirmed the test fails when the fix is reverted.
- Full `hdds-erasurecode` module test suite: 80 tests pass, 39 native tests
skipped (environment), no regressions.
- Note: This test must run in its own JVM (`reuseForks=false`) due to the
eagerly-initialized singleton.
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