import modin.pandas as pd
import numpy as np
import time
from modin.config import MinPartitionSize

num_columns = MinPartitionSize.get() + 1

# 3 rows where each row has the numbers from 0 through num_columns 
# exclusive in sequential order
# so the entire frame has a single row of two partitions,
# where the first has num_columns - 1 columns and the second has one.
df = pd.DataFrame(np.tile(np.arange(num_columns), (3, 1)))

# This takes hours for the the column containing 32,
# but should return much faster for the other columns.
def col_func(col):
    if col[0] == num_columns - 1:
        time.sleep(10000)
    return col * 2

# This blocks on the last column to recompute
# the column index, so it blocks 10000 seconds.
# instead, it should finish immediately while the last 
# apply completes asynchronously.
print('starting apply...')
result = df.apply(col_func)