[BUG] Compression doesn't compress data on SWMR



To reproduce:

  1. Build and run attached
    test980.c (1.4 KB)
    Observe the size of test.h5 is 5,705 bytes (correct).

  2. Uncomment


rebuild and run.
Now the file size exploded to 1,913,763 bytes!

Originally reported in in https://github.com/h5py/h5py/issues/980
(see more complete example there for motivation behind H5Fflushing repeatedly).

Best wishes,
Andrey Paramonov