Prefixes with most flags:

M 18
S 18
B 17
C 15
T 13
G 12
A 11
L 11
K 10

There are no flags with prefix X

Errors with threadpool:

$ python3 flags_threadpool2.py _

ZT failed: 503 - Service Temporarily Unavailable
ZU failed: 503 - Service Temporarily Unavailable
ZV failed: 503 - Service Temporarily Unavailable
ZY failed: 503 - Service Temporarily Unavailable
--------------------
24 flags downloaded.
37 not found.
615 errors.
Elapsed time: 3.86s


$ python3 flags_sequential2.py
Searching for 10 flags: BD, BR, CN, ID, IN, JP, NG, PK, RU, US
BD failed: (ProtocolError('Connection aborted.', gaierror(8, 'nodename nor servname provided, or not known')),)
--------------------
0 flag downloaded.
1 error.
Elapsed time: 0.02s
*** WARNING: 9 downloads never started! ***


194 flags downloaded.
482 not found.
Elapsed time: 683.71s

real	11m23.870s
user	0m3.214s
sys	0m0.603s


$ python3 flags2.py -a
LOCAL site: http://localhost:8001/flags
Searching for 194 flags: from AD to ZW
1 concurrent conection will be used.
--------------------
194 flags downloaded.
Elapsed time: 0.90s
(.env34) 192:countries luciano$ python3 flags2.py -e
LOCAL site: http://localhost:8001/flags
Searching for 676 flags: from AA to ZZ
1 concurrent conection will be used.
--------------------
194 flags downloaded.
482 not found.
Elapsed time: 4.71s
(.env34) 192:countries luciano$ python3 flags2.py -s remote
(.env34) 192:countries luciano$ python3 flags2.py -s remote -a -l 100
REMOTE site: http://python.pro.br/fluent/data/flags
Searching for 100 flags: from AD to LK
1 concurrent conection will be used.
--------------------
100 flags downloaded.
Elapsed time: 72.58s
(.env34) 192:countries luciano$ python3 flags2.py -s remote -e
REMOTE site: http://python.pro.br/fluent/data/flags
Searching for 676 flags: from AA to ZZ
1 concurrent conection will be used.
--------------------
194 flags downloaded.
482 not found.
Elapsed time: 436.09s
(.env34) 192:countries luciano$ python3 flags2_threadpool.py -s remote -e
REMOTE site: http://python.pro.br/fluent/data/flags
Searching for 676 flags: from AA to ZZ
30 concurrent conections will be used.
--------------------
194 flags downloaded.
482 not found.
Elapsed time: 12.32s
(.env34) 192:countries luciano$ python3 flags2_threadpool.py -s remote -e -m 100
REMOTE site: http://python.pro.br/fluent/data/flags
Searching for 676 flags: from AA to ZZ
100 concurrent conections will be used.
--------------------
89 flags downloaded.
184 not found.
403 errors.
Elapsed time: 7.62s
(.env34) 192:countries luciano$

wait_with_progress
http://compiletoi.net/fast-scraping-in-python-with-asyncio.html

http://blog.condi.me/asynchronous-part-1/