GH-45747: [C++] Remove deprecated ObjectType and FileStatistics, refactor hdfs code by AlenkaF · Pull Request #45998 · apache/arrow

AlenkaF · 2025-04-01T10:28:22Z

Rationale for this change

ObjectType and FileStatistics in io/hdfs.h have been deprecated for a while and can be removed.

What changes are included in this PR?

ObjectType and FileStatistics structs are removed and instead FileSystem API in arrow::fs is used. Together with this change, the hdfs connected code is moved from cpp/src/arrow/io to cpp/src/arrow/filesystem merging FileSystem and HadoopFileSystem classes from arrow::io into the public HadoopFileSystem class.

Are these changes tested?

Existing tests should pass.

Are there any user-facing changes?

Deprecated structs are removed and all hdfs related code is now a part of the filesystem module.

GitHub Issue: [C++] Remove deprecated ObjectType and FileStatistics #45747

Also closes: #22457 (not sure about io/interfaces.h?)

AlenkaF · 2025-04-01T12:56:21Z

Ah, this will not work. If we want to remove ObjectType and FileStatistics from io/hdfs.h and instead use FileSystem API, then filesystem component would have to be enabled by default. Also, if I understand correctly, we want to do a refactoring of io/hdfs anyways which would include the changes in this PR? (#22457)

cc @pitrou

pitrou · 2025-04-02T10:04:57Z

Ah, this will not work. If we want to remove ObjectType and FileStatistics from io/hdfs.h and instead use FileSystem API, then filesystem component would have to be enabled by default.

Well, ARROW_HDFS=ON could imply ARROW_FILESYSTEM=ON. I don't think that's a problem.

Also, if I understand correctly, we want to do a refactoring of io/hdfs anyways which would include the changes in this PR?

Yes, indeed. io/hdfs could be moved to filesystem/hdfs_internal or something similar.

AlenkaF · 2025-04-02T11:37:42Z

OK, I will then move io/hdfs to filesystem/hdfs_internal. Thanks!

AlenkaF · 2025-04-09T11:42:20Z

@pitrou I think this is ready for review. The failing builds have an issue opened: #46077

pitrou

Thanks for doing this @AlenkaF! Here are some comments.

pitrou · 2025-04-29T09:04:48Z

Are all these declarations actually needed by PyArrow?

No, most of them aren't and are copied from libarrow.pxd. I can remove the unused ones - but am not sure if some external application can actually use them?

pitrou · 2025-04-29T09:07:10Z

Don't we need to link to arrow::hadoop as was done above? cc @kou for advice

Hm, yeah. I will add a link as above as it makes sense.

Ah, it is there already (that explains why nothing failed =) )

arrow/cpp/src/arrow/CMakeLists.txt

Lines 857 to 861 in 53ef438

if(ARROW_HDFS)

foreach(ARROW_FILESYSTEM_TARGET ${ARROW_FILESYSTEM_TARGETS})

target_link_libraries(${ARROW_FILESYSTEM_TARGET} PRIVATE arrow::hadoop)

endforeach()

endif()

Not sure if the line with CMAKE_DL_LIBS is also needed here then?

pitrou · 2025-04-29T09:21:04Z

Ok, but we don't want to keep those two unofficial FileSystem and HadoopFileSystem classes which create confusion with the other (public) filesystem classes.

Ideally, those two classes disappear and their implementation code gets folded into the public HadoopFileSystem class.

If that's too annoying, we should at least merge those two classes and give them a less ambiguous name, for example HdfsClient.

Ok, will go with the disappearing =)
IIUC hdfs_io.h will be removed altogether:

FileSystem and HadoopFileSystem will go into hdfs.cc, folded into the public HadoopFileSystem

HdfsConnectionConfig will also go into hdfs.cc

declarations that are left will go into hdfs_internal.cc

pitrou · 2025-04-29T09:22:19Z

Most of these declarations should IMHO go into the arrow::filesystem::internal namespace, except for HdfsConnectionConfig which can go into arrow::filesystem.

AlenkaF · 2025-05-19T09:57:13Z

Hi @pitrou, could you please take a quick look at the changes when you have a moment?

I've done my best to implement the suggested changes, but am sure there's still room for improvement.
A couple of issues I could use your input on:

Some C++ tests are failing in hdfs_test, with the following error:

/arrow/cpp/src/arrow/filesystem/hdfs_test.cc:90: HadoopFileSystem::Make failed, it is possible when we don't have proper 
driver on this node, err msg is IOError: Unable to load libjvm

I'm not sure how best to resolve this — any guidance would be appreciated.

The MSVC compiler is complaining about a forward-declared friend function I'm using in hdfs.cc. Do you have any advice on how to better organise this?

The Python and MATLAB test failures are not related.
Thanks in advance!

pitrou · 2025-05-19T12:38:53Z

Hi @AlenkaF

Some C++ tests are failing in hdfs_test, with the following error:

I think you're misreading the output, the test is actually skipped when the driver fails unloading, which is normal:

(...)
dlopen(/usr/java/latest//lib/amd64/server/libjvm.so) failed: /usr/java/latest//lib/amd64/server/libjvm.so: cannot open shared object file: No such file or directory
/arrow/cpp/src/arrow/filesystem/hdfs_internal.cc:294  try_dlopen(libjvm_potential_paths, "libjvm")
/arrow/cpp/src/arrow/filesystem/hdfs.cc:95  ConnectLibHdfs(&driver_)
/arrow/cpp/src/arrow/filesystem/hdfs.cc:725  ptr->impl_->Init()
/arrow/cpp/src/arrow/filesystem/hdfs_test.cc:205: Skipped
Driver not loaded, skipping

https://github.com/apache/arrow/actions/runs/15109276550/job/42464862030?pr=45998#step:7:3277

The problem is in the other tests, because it seems a destructor crashes:


[ RUN      ] TestHadoopFileSystem.DeleteDirContents
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Running '/build/cpp/debug/arrow-hdfs-test' produced core dump at '/tmp/core.arrow-hdfs-test.25630', printing backtrace:
[New LWP 25630]
[New LWP 25631]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/build/cpp/debug/arrow-hdfs-test'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007fc37b23d5be in arrow::io::internal::LibHdfsShim::Disconnect () at /arrow/cpp/src/arrow/filesystem/hdfs_internal.cc:340
340	int LibHdfsShim::Disconnect(hdfsFS fs) { return this->hdfsDisconnect(fs); }
[Current thread is 1 (Thread 0x7fc374633dc0 (LWP 25630))]
(...)

https://github.com/apache/arrow/actions/runs/15109276550/job/42464862030?pr=45998#step:7:3281

pitrou · 2025-05-19T12:41:21Z

The MSVC compiler is complaining about a forward-declared friend function I'm using in hdfs.cc. Do you have any advice on how to better organise this?

Hmm, rather than trying to find the exact explanation, a simple solution would be to change these functions into static methods, for example this:

ARROW_EXPORT Status MakeReadableFile(const std::string& path, int32_t buffer_size,
  const io::IOContext& io_context, LibHdfsShim* driver,
  hdfsFS fs, hdfsFile file,
  std::shared_ptr<HdfsReadableFile>* out);

would become:

class ARROW_EXPORT HdfsReadableFile : public RandomAccessFile {
 public:
   (...)

  static Result<std::shared_ptr<HdfsReadableFile>> Make(
      const std::string& path, int32_t buffer_size,
      const io::IOContext& io_context, LibHdfsShim* driver,
      hdfsFS fs, hdfsFile file);

AlenkaF · 2025-05-19T12:41:24Z

Aha, I see! Thanks, will look into it.

AlenkaF · 2025-05-20T13:57:00Z

@pitrou I cleaned up the CI failures (others are not related) and am hoping this changes will not be too bad to review :)

benibus

Thanks! This looks pretty good to me. Just a few comments.

AlenkaF · 2025-06-10T11:53:40Z

@benibus @pitrou would you mind taking another look?

AlenkaF · 2025-06-23T13:44:09Z

@pitrou gentle ping. Would I be too optimistic to try to get it into 21.0.0?

Copilot

Pull request overview

Copilot reviewed 17 out of 17 changed files in this pull request and generated 3 comments.

AlenkaF · 2026-07-01T12:22:02Z

PR is ready for another round of review (suggestions applied, code rebased and liners run).

raulcd

@AlenkaF not thoroughly reviewing, I am just trying to understand the expected architecture a little better before further review.

raulcd · 2026-07-06T08:49:49Z

+    }                                                           \
+  } while (0)
+
+static constexpr int kDefaultHdfsBufferSize = 1 << 16;


this seems to be copied from cpp/src/arrow/io/hdfs.cc
Do we require code on both filesystem and io? Should we have a common place instead of repeating code?Reading the description of the PR I thought we were completely removing cpp/src/arrow/io/hdfs.cc but the file seems to be there. What is the code that should land here on the other?

github-actions Bot added Component: C++ awaiting review Awaiting review Component: Python labels Apr 1, 2025

AlenkaF force-pushed the gh-45747-remove-deprecated-ObjectType-FileStatistics branch from e95f3f3 to 287cb9b Compare April 8, 2025 13:24

AlenkaF changed the title ~~GH-45747: [C++] Remove deprecated ObjectType and FileStatistics~~ GH-45747: [C++] Remove deprecated ObjectType and FileStatistics, refactor hdfs code Apr 9, 2025

AlenkaF marked this pull request as ready for review April 9, 2025 11:40

AlenkaF force-pushed the gh-45747-remove-deprecated-ObjectType-FileStatistics branch from 1bd3f43 to 8e26730 Compare April 28, 2025 05:10

AlenkaF requested review from raulcd and rok as code owners April 28, 2025 05:10

pitrou reviewed Apr 29, 2025

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github-actions Bot added awaiting committer review Awaiting committer review and removed awaiting review Awaiting review labels Apr 29, 2025

AlenkaF marked this pull request as draft May 19, 2025 07:36

AlenkaF marked this pull request as ready for review May 27, 2025 09:37

AlenkaF requested a review from pitrou May 27, 2025 09:37

AlenkaF force-pushed the gh-45747-remove-deprecated-ObjectType-FileStatistics branch from 72eae6e to 7810940 Compare June 5, 2025 08:38

benibus reviewed Jun 10, 2025

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Comment thread cpp/src/arrow/filesystem/hdfs_internal.h Outdated

Comment thread cpp/src/arrow/filesystem/hdfs.h Outdated

AlenkaF commented Jun 10, 2025

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Comment thread python/pyarrow/includes/libarrow_fs.pxd Outdated

AlenkaF force-pushed the gh-45747-remove-deprecated-ObjectType-FileStatistics branch from c7beefc to 281b51a Compare June 23, 2025 13:13

AlenkaF added 20 commits July 1, 2026 12:08

Try to safeguard client_ from nullptr and dangling ptr

f145af4

Update hdfs Impl

b9df46d

Change io::internal to fs::internal

5667b50

Run C++ linter

e153876

Remove HdfsDriver from PyArrow Cython file

43d5890

Run pre-commit

0421e6f

Fix failing CI builds

607bb1c

Add <unordered_map>

e8b723f

Update HdfsConnectionConfig comment

6c38487

Update meson.build

a3b8b54

Fix MakeDirectory

8cbd147

Update Copy

67a20c7

Move internal hdfs methods back to public

a518fef

Update tests

060ce86

Run pre-hook

ed209f5

Remove internal tests

b9aab57

Add #undef for CHECK_FAILURE

92304a3

Add newline at the end of the file

24b29c5

Remove legacy methods

7d3afea

Remove HdfsConnectionConfig

fcea572

Copilot AI review requested due to automatic review settings July 1, 2026 10:09

AlenkaF force-pushed the gh-45747-remove-deprecated-ObjectType-FileStatistics branch from b10f159 to fcea572 Compare July 1, 2026 10:09

Copilot started reviewing on behalf of AlenkaF July 1, 2026 10:12 View session

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Comment thread python/pyarrow/_hdfs.pyx

Comment thread python/pyarrow/includes/libarrow_fs.pxd Outdated

Comment thread python/pyarrow/io.pxi

AlenkaF added 2 commits July 1, 2026 12:27

Use internal::ConnectLibHdfs

e1136c3

Fix Python bindings

972f7a4

raulcd reviewed Jul 6, 2026

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github-actions Bot added awaiting changes Awaiting changes and removed awaiting committer review Awaiting committer review labels Jul 6, 2026

	if(ARROW_HDFS)
	foreach(ARROW_FILESYSTEM_TARGET ${ARROW_FILESYSTEM_TARGETS})
	target_link_libraries(${ARROW_FILESYSTEM_TARGET} PRIVATE arrow::hadoop)
	endforeach()
	endif()

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AlenkaF commented Apr 1, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Rationale for this change

What changes are included in this PR?

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Are there any user-facing changes?

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AlenkaF commented Apr 1, 2025

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pitrou commented Apr 2, 2025

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AlenkaF commented May 19, 2025

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AlenkaF commented Apr 1, 2025 •

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