memoryview(direct ByteBuffer) has incorrect nbytes field

[Karl Nelson]

There appears to be a bug in the nbytes on some systems when using direct byte buffer. This prevents them from being used with io.readinto

Bug replication

>>> import jpype
>>> import jpype.imports
>>> jpype.startJVM()
>>> from java.nio import ByteBuffer
>>> memoryview(ByteBuffer.allocateDirect(100)).nbytes
25096256

[Stig Oskar Ofstad]

Hi, any plans to make a new release soon? I'm running into what I believe to be this bug when unpickling jpype objects. Causing BufferOverflowException.

File "/opt/project/src/common/stateful_calculations.py", line 41, in get_stored_state_object
  loaded = jpype.pickle.JUnpickler(fd).load()
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/code/.venv/lib/python3.11/site-packages/jpype/pickle.py", line 161, in __call__
     return decoder.unpack(args[0])
            ^^^^^^^^^^^^^^^^^^^^^^^
 java.nio.java.nio.BufferOverflowException: java.nio.BufferOverflowException

Also; this print(memoryview(jpype.java.nio.ByteBuffer.allocateDirect(100)).nbytes) outputs some varying large numbers like 52175792

Thanks for a great library! 🙂

[Martin K. Scherer]

Until the next release you could just use the a development version as such:
pip install git+https://github.com/jpype-project/jpype

[Stig Oskar Ofstad]

Does that really work? Considering how this library compiles .so files that is distributed along with the package.

[Karl Nelson]

Sorry I have been so slow. I was hoping to get a few things addressed before the next release, but I haven't had much time. I will try to wrap them up and get out a release this month.