Siyao Meng created HDDS-17155:
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Summary: NativeLibraryLoader extracts libozone_rocksdb_tools.so
into the working directory instead of java.io.tmpdir
Key: HDDS-17155
URL: https://issues.apache.org/jira/browse/HDDS-17155
Project: Apache Ozone
Issue Type: Bug
Components: Native
Reporter: Siyao Meng
Assignee: Siyao Meng
Attachments: HDDS-17155.001.patch
h3. Problem
{{NativeLibraryLoader}} loads {{libozone_rocksdb_tools.so}} in two steps:
# It tries {{System.loadLibrary}} from {{java.library.path}}. The
distribution's {{lib/native}} only contains {{libhadoop}}, so this misses.
# It extracts the library from {{hdds-rocks-native-*.jar}} into
{{native.lib.tmp.dir}}. If that property is not set, it uses {{new
File("").getAbsoluteFile()}}, the *current working directory*.
No Ozone script sets {{native.lib.tmp.dir}}. Whenever the process cannot write
to its working directory, extraction fails and the library is not loaded:
{code}
WARN utils.NativeLibraryLoader: Unable to load library: ozone_rocksdb_tools
java.nio.file.AccessDeniedException:
/opt/hadoop/ozone_rocksdb_tools7373108702252003876
WARN snapshot.SnapshotDiffManager: Native Library for raw sst file reading
loading failed. Fallback to performing a full diff instead. ...
{code}
This was hit in the compose runner image: the OM runs in {{/opt/hadoop}}, the
mounted distribution, and that directory was not writable by the container
user. The fallback is silent apart from the WARN, so snapshot diff quietly
loses the native path. {{ozone debug checknative}} then reports {{rocks-tools:
false}} for this reason, which would also mask the libstdc++ problem in
HDDS-17153.
For comparison:
* Hadoop's {{NativeCodeLoader}} only uses {{System.loadLibrary}} from
{{lib/native}} and never extracts.
* RocksJava's own {{NativeLibraryLoader}} extracts {{librocksdbjni}} into
{{java.io.tmpdir}} by default ({{File.createTempFile}}), or into
{{ROCKSDB_SHAREDLIB_DIR}}.
h3. Fix
When {{native.lib.tmp.dir}} is not set (or empty), create the extraction
directory with {{Files.createTempDirectory(libraryName)}}, i.e. under
{{java.io.tmpdir}}. An explicit {{native.lib.tmp.dir}} behaves as before.
Cleanup is unchanged: the existing shutdown hook deletes the directory.
h3. Testing done
* {{TestNativeLibraryLoader#testDummyLibrary}} now expects the library under
{{java.io.tmpdir}} when the property is {{null}} or empty. Previously it
expected the working directory.
** Without the fix, those two cases fail ({{Expecting actual not to be
empty}}). With the fix, they pass.
** The explicit-directory case still passes.
* Native build ({{-Drocks_tools_native}}) on master: TestNativeLibraryLoader
(6, including the real {{ozone_rocksdb_tools}} load),
TestManagedRawSSTFileIterator (28), TestLatestVersionedKWayMergeIterator (10)
and TestLatestVersionedKWayMergeIteratorOverSst (2) all pass. Nothing was
extracted into the module directory.
* Checkstyle is clean.
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