Ask questionsBoto3 causing segmentation fault

In some special circumstance, using boto3 will cause segmentation fault.

The code that can reproduce it is as follows. There are totally 3 files (and one subdirectory) need to be created because I am not able to reproduce it with only one file. You can also clone from


import sys
import boto3

def foo():
    bar(boto3.resource('dynamodb', region_name='us-east-2'))
    sys.exit(0)  # Unable to reproduce without this line

# Unable to reproduce if merge this function with foo()
def bar(dynamodb):
    import mypackage.justtyping  # Unable to reproduce without this line

    # Unable to reproduce if do not get item twice, or use `dynamodb` in both
    # cases, or create new resource in both cases.
    # Note that the table must exist, but it does not need to have the item.
    dynamodb.Table('sigsegv').get_item(Key={'pkey': 'xxx'})
    boto3.resource('dynamodb', region_name='us-east-2').Table('sigsegv').get_item(Key={'pkey': 'xxx'})


from typing import Sequence
x = Sequence['xxx']  # Unable to reproduce without this line, or replace string `'xxx'` with a class (e.g. `bytes`)


import mypackage

Run the code and get the segmentation fault:

$ python3
[1]    26495 segmentation fault (core dumped)  python3

Versions: python 3.5.2, boto3 1.4.4, ubuntu 16.04.2


Answer questions chrisdlangton

i am also seeing segfault #2534 but only when using S3, in my testing i went back to python 3.7 and saw the error existed so i ruled out it being a python bug and didn't go back further.

I think there might be a commonality somewhere in boto3 session code paths, if we assume there is a connection.


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