Drop LoadLibrary by amos402 · Pull Request #880 · pythonnet/pythonnet · GitHub

What does this implement/fix? Explain your changes.

There are some limitations to dynamic load a library on some systems(e. g. Android).
LoadLibrary just called for once for getting the _PyObject_NextNotImplemented,
we can use another ways to get this function.

Does this close any currently open issues?

No

Any other comments?

Checklist

Check all those that are applicable and complete.

Make sure to include one or more tests for your change
If an enhancement PR, please create docs and at best an example
Add yourself to AUTHORS
Updated the CHANGELOG

I'll have to look a bit more into this. I thought that this LoadLibrary call there is not only pulling in that one symbol but that it serves as a "proxy" to enforce loading the library into memory s.t. the P/Invoke bindings work. Since your patch passes all tests (apart from the known failing one) I must have misunderstood something and will test this in our use-case to verify. Thank you already for your contribution, if this works out this will help a lot in simplifying the build process :)

@filmor @amos402 I made a single Python.Runtime.dll to work with any Python 3.x interpreter in my fork (could have included 2.x, but its lifetime is ending) via extensive use of LoadLibrary and related methods. Which I intended to upstream once 2.7 is dropped (or, for example, if we had a separate 2.x branch in maintenance mode).

@lostmsu What do you mean by "extensive use"? Isn't it enough to load libpython*.so once at startup? Could you point me to that code?

@filmor well, the LoadLibrary is called once, but all the functions are obtained using GetProcAddress/dlsym.
See losttech@672258f

And also losttech@80aa07f

All of that happens once at startup too. But there are many functions.

There is probably a performance impact too, due to the use of delegates in place of PInvoke calls.

@lostmsu What's your conclusion on keeping LoadLibrary? Does the code using delegates run reasonably or not?

Seems like you should delete these lines too, and line 295 as well since you moved it below.

This seems a quite reasonable patch, I think we should merge it.

I've had trouble in the past with this LoadLibrary/FreeLibrary screwing up the dlopen flags.

* Drop C module dependency when getting _PyObject_NextNotImplemented * Exception details for SetNoSiteFlag

Codecov Report

Merging #880 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #880   +/-   ##
=======================================
  Coverage   86.71%   86.71%           
=======================================
  Files           1        1           
  Lines         301      301           
=======================================
  Hits          261      261           
  Misses         40       40

Flag	Coverage Δ
#setup_linux	65.44% <ø> (ø)	⬆️
#setup_windows	71.42% <ø> (ø)	⬆️

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I removed the dependency of zipimport. But still have no solution for SetNoSiteFlag, maybe we should add a docs for it(like please use -S when using static compile).

Can you throw more informative exception? Win32Exception would automatically read last error on Windows, but I don't know what to do for *nix

Generally it should throw inside from Load, the nullptr checking just for in case(if the loader implementation didn't throw an exception). I'm not going to insert any platform specific code here.

Can PyEval_GetBuiltins() return an error?

From the docs it doesn't look like it can (https://docs.python.org/3/c-api/reflection.html#c.PyEval_GetBuiltins).

The globals dict is needed, but we don't seem to be using the __builtins__ in the string. Do we really need this line?

If you don't setup a __builtins__ or set object explicit, object may not be found.

You might want to construct an instance of PythonException before doing XDecref, otherwise last error could potentially be overwritten by XDecref with something new.

…en-2

Why should this not be supported? The symbol is just in the running DLL, so loader.Load(_PythonDll) has to return essentially the result of dlopen(NULL, ...).

Yes, it should be supported. Just a mistake according to my wrong tests. I will recover it back.

I believe issues #891, #946, and #967 all point to a fundamental problem with this PR.

On certain Linux distributions (Debian for example), Python C extension libraries are deliberately not linked to libpython.

Yet .NET Core's [DllImport] does not load libpython with RTLD_GLOBAL.

So if this PR removes dllLocal = loader.Load(_PythonDll); from runtime.cs, where the salient line in LibraryLoader.cs is var res = dlopen(filename, RTLD_NOW | RTLD_GLOBAL);, won't this PR break Python.NET's "Embedding" mode on .NET Core?

As Victor Stinner put it in Python issue issue 21536:

...libpython must always be loaded with RTLD_GLOBAL.

Unless we can get [DllImport] to set the RTLD_GLOBAL flag, I'm afraid we need the explicit loader.Load, at least for Linux .NET Core embedding.

* Pick `SlotHelper` from pythonnet#958

@Jeff17Robbins This PR won't break "Embedding" mode on .NET Core, moreover it improve the compatibility since it didn't need call the dlopen.

Contained in #958

amos402 added 3 commits June 14, 2019 02:35

Drop LoadLibrary dependency

d1928dc

Explain for getting _PyObject_NextNotImplemented

f000e08

Update changelog and authors

f882400

filmor and others added 3 commits June 20, 2019 19:29

Merge branch 'master' into drop-dlopen

b7715ee

Merge remote-tracking branch 'remotes/upstream/master' into drop-dlopen

41ac665

Merge branch 'master' into drop-dlopen

c6dae9e

benoithudson reviewed Nov 21, 2019

View reviewed changes

Merge branch 'master' into drop-dlopen

653a263

amos402 force-pushed the drop-dlopen branch from 4d9c632 to 18d8da4 Compare December 1, 2019 13:35

* Load PyModuleType without LibraryLoader

b3e889b

* Drop C module dependency when getting _PyObject_NextNotImplemented * Exception details for SetNoSiteFlag

amos402 force-pushed the drop-dlopen branch from 18d8da4 to b3e889b Compare December 1, 2019 13:40

lostmsu reviewed Dec 3, 2019

View reviewed changes

amos402 mentioned this pull request Dec 14, 2019

Optimize for Runtime.InitializePlatformData #891

Closed

amos402 added 2 commits December 15, 2019 02:26

Merge remote-tracking branch 'remotes/upstream/master' into drop-dlop…

04d6dfb

…en-2

Prevent exception override

5150e61

filmor reviewed Dec 15, 2019

View reviewed changes

Rollback symbol loading for __Internal

65e209e

amos402 added 3 commits February 13, 2020 01:07

Merge branch 'master' into drop-dlopen

431d644

* Fix refcnt error

2b84394

* Pick `SlotHelper` from pythonnet#958

Merge 'master' into drop-dlopen

b7797d3

amos402 mentioned this pull request Feb 13, 2020

Add soft shutdown #958

Merged

4 tasks

amos402 closed this Oct 9, 2020

		@@ -297,16 +297,20 @@ internal static void Initialize(bool initSigs = false)
		IntPtr dllLocal = IntPtr.Zero;
		var loader = LibraryLoader.Get(OperatingSystem);

+                          if (dllLocal == IntPtr.Zero)
                           {
-                              dllLocal = loader.Load(_PythonDll);
+                              throw new Exception($"Cannot load {_PythonDll}");

+                      private static IntPtr Get_PyObject_NextNotImplemented()
+                      {
+                          IntPtr globals = PyDict_New();
+                          if (PyDict_SetItemString(globals, "__builtins__", PyEval_GetBuiltins()) != 0)

                       {
+                          if (_PythonDll == "__Internal")
+                          {
+                              throw new NotSupportedException("SetNoSiteFlag didn't support on static compile");

		XDecref(globals);
		throw new PythonException();

Drop LoadLibrary by amos402 · Pull Request #880 · pythonnet/pythonnet · GitHub

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Drop LoadLibrary - #880

Drop LoadLibrary#880amos402 wants to merge 14 commits intopythonnet:masterpythonnet/pythonnet:masterfrom amos402:drop-dlopenamos402/pythonnet:drop-dlopenCopy head branch name to clipboard

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amos402 commented Jun 13, 2019 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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What does this implement/fix? Explain your changes.

Does this close any currently open issues?

Any other comments?

Checklist

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filmor commented Jun 13, 2019

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lostmsu commented Jun 13, 2019

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filmor commented Jun 13, 2019

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lostmsu commented Jun 13, 2019 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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filmor commented Sep 12, 2019

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codecov-io commented Dec 1, 2019 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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amos402 commented Dec 1, 2019

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Jeff17Robbins commented Dec 15, 2019

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amos402 commented Feb 13, 2020

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amos402 commented Oct 9, 2020

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Drop LoadLibrary#880
amos402 wants to merge 14 commits into
pythonnet:masterfrom
amos402:drop-dlopen

amos402 commented Jun 13, 2019 •
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lostmsu commented Jun 13, 2019 •
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codecov-io commented Dec 1, 2019 •
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