h5_create_read_write_issue.py

import h5py
import numpy
import time
import sys
from multiprocessing import Process


FNAME = 'foo.h5'


class Reader(Process):
    """Just a process that opens the file for reading and keeps it open
    Note: I use a separate process to avoid a "File already Open" exception
    """
    def run(self):
        print("READER: Open file for read")
        f = h5py.File(FNAME, 'r', libver='latest')
        time.sleep(100)
        f.close()

def open_for_read():
    """ open the file for read and keep it open"""
    reader = Reader()
    reader.start()
    time.sleep(1) # just give time to the reader to open before continuing
    return reader

def initialize_file():
    """create a file containing a dataset"""
    f = h5py.File(FNAME,'w', libver='latest')
    f.create_dataset('data', data=numpy.arange(5))
    f.close()

def open_for_append():
    """open the file for appending"""
    f = h5py.File(FNAME, 'a', libver='latest')
    f.close()


if __name__ == '__main__':
    print("hdf5_version=", h5py.version.hdf5_version)

    initialize_file()
    reader = open_for_read()
    try:
        # open for append while it is open for read by another process 
        # fails with hdf5_version=1.10.0  (but not with 1.8.16)
        open_for_append()
    finally:
        reader.terminate()

    print("OK. Finish")