low-level client + thread-safety question

[Gatsby-Lee]

Hi,

I have a question about thread-safety in low-level client.
ref: https://boto3.amazonaws.com/v1/documentation/api/latest/guide/clients.html#multithreading-or-multiprocessing-with-clients

I went through the link. ( I also read one in Resource and Session )
I don't understand this sentence.

Shared Metadata: Clients expose metadata to the end user through a few attributes (namely meta, exceptions and waiter_names). These are safe to read but any mutations should not be considered thread-safe.

What use case requires to change the value of the attributes, meta, exceptions and waiter_names?
And, why it's not thread-safe?
How can it be fully thread-safe? ( deep-copy of the response? )

Thank you
Gatsby

[tim-finnigan]

Hi @Gatsby-Lee thanks for reaching out. I think that those attributes you referenced should generally not be mutated in order to maintain consistent and expected responses from service APIs. And it's not considered thread-safe to do that because the AWS CLI doesn't have a mechanism for guaranteeing that the properties would stay the same through the entire request process across threads.

The example provided here is the recommended way to do multi-threading: https://boto3.amazonaws.com/v1/documentation/api/latest/guide/clients.html#general-example.

[Gatsby-Lee]

@tim-finnigan Hi, Thank you for your response.
Based on your comment and the doc, I understand that mutation in those properties are not thread-safe.

My question is that who wants to change these properties with what use cases?
Typically ( maybe myself ), all I want to do with boto3 is "making API call to AWS" and "working with the response from AWS".

When do I want to touch those properties, especially "exceptions"?

Thank you
Gatsby