Python Bindings hang on read

[NAThompson]

Following this example, but without MPI, I get a hang with the following code:

#!/usr/bin/env python3

import math
import argparse
import adios2

def run():
    parser = argparse.ArgumentParser(description=('Graphically displays output of Kortweg-de Vries simulation'))
    arg = parser.add_argument("-f", "--filename", help=".bp filename/directory (default: kdv.bp)", default="kdv.bp")

    options = parser.parse_args()
    
    with adios2.open(options.filename, "r") as file_handle:
        print("opened file")
        for step in file_handle:
            points = file_handle.read("u")
            print("Done showing step")

        print("Done going through steps")

if __name__ == '__main__':
    run()

The statement "Done going through steps" is never printed.

(Note: it also hangs if I do step.read("u").)

The file is produced by the simulation in this PR; this file is successfully examined by bpls:

$ bpls ~/ADIOS2/build/kdv.bp -lav
File info:
  of variables:  1
  of attributes: 3
  statistics:    Min / Max

  double   dx              attr   = 0.0078125
  string   interpretation  attr   = "Equispaced"
  double   u               311*{256} = -1 / 2.71997
  double   x0              attr   = 0

Extra info:

$ python3 --version
Python 3.7.5
$  conda --version
conda 4.8.3
$ python3 -q
>>> import adios
>>> adios2.__version__
'2.5.0.2'

[williamfgc]

try:

for step_handle in file_handle:
    points = step_handle.read("u")

check also with the latest master

[NAThompson]

Just tried your suggestion; no joy.

Sadly I can't get the Python bindings to compile on master due to #2047.