Why thread and queue only process the last row

[kinojom]

CSv date,ref_num,desc,debit,credit,payee_id,code,name 2019-01-31,L00001,john,30.00,,150,500,johnkino 2019-01-31,L00001,john,,30.00,150,600,johnkino 2019-01-30,L00002,john,30.00,,150,500,johnkino 2019-01-30,L00002,john,,30.00,150,600,johnkino

import csv from itertools import groupby import threading from queue import Queue def postRequest(): print('thread starting') while True: item_to_process = q.get() print(item_to_process) q.task_done() q = Queue() with open("test.csv", "r") as csv_ledger: r = csv.DictReader(csv_ledger) data = [ dict(d) for d in r ] groups = {} for k, g in groupby(data, lambda r: (r[ 'ref_num' ])): items = [ ] for i in g: chart_of_account = {k: v for k, v in i.items() if k in [ 'name', 'code' ]} item = {k: v for k, v in i.items() if k in [ 'debit', 'credit', 'desc', 'payee_id' ]} item.update({'chart_of_account': chart_of_account}) items.append(item) groups.update({ "date": i[ 'date' ], "desc": i[ 'desc' ], "ref_num": k, "items": items }) print(groups) <--- correct structure q.put(groups) for i in range(1): t = threading.Thread(target=postRequest) t.start() print('Main thread waiting') q.join() print('Done.')

Result

2019-01-30,L00002,john,,30.00,150,600,johnkino 2019-01-30,L00002,john,,30.00,150,600,johnkino 2019-01-30,L00002,john,,30.00,150,600,johnkino 2019-01-30,L00002,john,,30.00,150,600,johnkino

The data of groups is the complete and correct data structure which is loop every row but the result always loops for the last row only after passing to queue for processing.