def _get_coverage_data():
    """
    Make a singleton ``CoverageData``.
    Avoid writing to disk. Other processes can corrupt the file.
    """
    covdata = coverage.CoverageData(no_disk=True)
    cov = get_active_coverage()
    assert cov is not None, "no active Coverage instance"

    @atexit.register
    def _finalize():
        # Update active coverage
        cov.get_data().update(covdata)

    return covdata

    Make a singleton ``CoverageData``.
    Avoid writing to disk. Other processes can corrupt the file.
    
numba/misc/coverage_support.py