tensorflow 2.0 keras save model to hdfs: Can't decrement id ref count

I have mounted an hdfs drive by hdfs fuse, thus I can access the hdfs by path /hdfs/xxx.

After training a model by keras, I want to save it to /hdfs/model.h5 by model.save("/hdfs/model.h5").

I get the following error:

2020-02-26T10:06:51.83869705Z   File "h5py/_objects.pyx", line 193, in h5py._objects.ObjectID.__dealloc__
2020-02-26T10:06:51.838791107Z RuntimeError: Can't decrement id ref count (file write failed: time = Wed Feb 26 10:06:51 2020
2020-02-26T10:06:51.838796288Z , filename = '/hdfs/model.h5', file descriptor = 3, errno = 95, error message = 'Operation not supported', buf = 0x7f20d000ddc8, total write size = 512, bytes this sub-write = 512, bytes actually written = 18446744073709551615, offset = 298264)
2020-02-26T10:06:51.838802442Z Exception ignored in: 'h5py._objects.ObjectID.__dealloc__'
2020-02-26T10:06:51.838807122Z Traceback (most recent call last):
2020-02-26T10:06:51.838811833Z   File "h5py/_objects.pyx", line 193, in h5py._objects.ObjectID.__dealloc__
2020-02-26T10:06:51.838816793Z RuntimeError: Can't decrement id ref count (file write failed: time = Wed Feb 26 10:06:51 2020
2020-02-26T10:06:51.838821942Z , filename = '/hdfs/model.h5', file descriptor = 3, errno = 95, error message = 'Operation not supported', buf = 0x7f20d000ddc8, total write size = 512, bytes this sub-write = 512, bytes actually written = 18446744073709551615, offset = 298264)
2020-02-26T10:06:51.838827917Z Traceback (most recent call last):
2020-02-26T10:06:51.838832755Z   File "/usr/local/lib/python3.6/dist-packages/tensorflow_core/python/keras/saving/hdf5_format.py", line 117, in save_model_to_hdf5
2020-02-26T10:06:51.838838098Z     f.flush()
2020-02-26T10:06:51.83885453Z   File "/usr/local/lib/python3.6/dist-packages/h5py/_hl/files.py", line 452, in flush
2020-02-26T10:06:51.838859816Z     h5f.flush(self.id)
2020-02-26T10:06:51.838864401Z   File "h5py/_objects.pyx", line 54, in h5py._objects.with_phil.wrapper
2020-02-26T10:06:51.838869302Z   File "h5py/_objects.pyx", line 55, in h5py._objects.with_phil.wrapper
2020-02-26T10:06:51.838874126Z   File "h5py/h5f.pyx", line 146, in h5py.h5f.flush
2020-02-26T10:06:51.838879016Z RuntimeError: Can't flush cache (file write failed: time = Wed Feb 26 10:06:51 2020
2020-02-26T10:06:51.838885827Z , filename = '/hdfs/model.h5', file descriptor = 3, errno = 95, error message = 'Operation not supported', buf = 0x4e5b018, total write size = 4, bytes this sub-write = 4, bytes actually written = 18446744073709551615, offset = 34552)

But I can directly write a file to the same path by

with open("/hdfs/a.txt") as f:
    f.write("1")

Also I've figured out a tricky workaround and it worked...

model.save("temp.h5")
move("temp.h5", "/hdfs/model.h5")

So maybe the problem is about keras api? It can only save the model locally but cannot save to an hdfs path.

Any idea how to fix the problem?

Solution

I don't think tensorflow makes any promises about being able to save to hdfs-fuse. Your (final) error is "Can't flush cache" not, "Can't decrement id ref count", basically meaning "Can't save straight to hdfs-fuse". But, to be honest, it seems fixed to me, your workaround is fine.