[Ruby] ApiClient is not threadsafe when downloading files

[dawson-conway]

Description

By default, the ruby client uses one ApiClient across all threads. This would be fine, but when downloading files, the ApiClient stores the tempfile reference in an instance variable. This leads to a race condition if two threads are making a call to an endpoint that downloads files at the same time, both calls may return the same file. So

Steps to reproduce

In two parallel threads, use the same Api Client to hit endpoints that download different files. It's a race condition, so it won't happen every time.

Suggest a fix/enhancement

Either the ApiClient.default() needs to return a thread-specific API client, or the tempfile needs to be stored in a thread-safe way (either a thread variable or local variable)

[wing328]

By default, the ruby client uses one ApiClient across all threads.

for the time being what about creating an instance of ApiClient per API classes (e.g. PetApi)?

[wing328]

the ApiClient stores the tempfile reference in an instance variable.

Another approach is to refactor the code a bit to avoid using the instance variable to store the temp file.

Is that something you can help us with? I can point you to some good starting points.

[dawson-conway]

for the time being what about creating an instance of ApiClient per API classes (e.g. PetApi)?

Our current workaround is to create an instance of ApiClient per request (technically we could do per thread, but that was a larger refactor, and it's pretty cheap to instantiate.)

Is that something you can help us with? I can point you to some good starting points.

I've created a fork with some changes that I think solve the problem. I need some help testing them.

master...dawson-conway:openapi-generator:16796_threadsafe_ruby