[BUILD-439] perf: Prevent Anki being laggy while downloading media

[RisingOrange]

Some users are experiencing Anki being laggy when the AnkiHub media sync is in progress.

This PR addresses the problem by:

• re-using requests.Session objects
• reducing the max_workers argument of the ThreadPoolExecutor instances that download and upload media

Related issues

https://ankihub.atlassian.net/jira/software/c/projects/BUILD/boards/1?selectedIssue=BUILD-439 https://theanking.slack.com/archives/C03S5DH9HH9/p1717080091231869

Proposed changes

• Re-use a requests.Session thread-locally
• Use this max_workers value: https://github.com/ankipalace/ankihub_addon/blob/bb1b2c9cc55a7aa06f14bfa25682f60a51e96788/ankihub/ankihub_client/ankihub_client.py#L115-L118 This reduces the number of max_workers by 3 for most devices when compared to the default setting. The advantage of this is that the amount of workers is based on the device and the reduction will be relatively large on devices with low cpu counts, but relatively small on devices with high cpu counts.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 87.51%. Comparing base (14d9af6) to head (3538b11). Report is 6 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #972 +/- ## ========================================== + Coverage 87.41% 87.51% +0.10% ========================================== Files 66 66 Lines 6642 6697 +55 ========================================== + Hits 5806 5861 +55 Misses 836 836 ```

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[RisingOrange]

@andrewsanchez Good points!

I changed the client to use one Session for each thread. The Session is re-used for requests on that thread.

The performance improvements from using a Session properly will depend on us instantiating the client only once when it is being used for multiple requests.

This is now the case, at least when downloading and uploading media (where it matters most). AnkiHubClient.download_media takes the list of all media names that need to be downloaded, so everything will be handled by one client instance. The same goes for AnkiHubClient.upload_media.

[sentry-io[bot]]

Suspect Issues

This pull request was deployed and Sentry observed the following issues:

• ‼️ AnkiHubRequestException: AnkiHub request exception: HTTPSConnectionPool(host='ankihub.s3.amazonaws.com', port=443): Max re... 1322529746.ankihub_client.ankihub_client in _se... View Issue
• ‼️ AnkiHubRequestException: AnkiHub request exception: HTTPSConnectionPool(host='ankihub.s3.amazonaws.com', port=443): Max re... 1322529746.ankihub_client.ankihub_client in _se... View Issue
• ‼️ AnkiHubRequestException: AnkiHub request exception: HTTPSConnectionPool(host='app.ankihub.net', port=443): Max retries exc... 1322529746.ankihub_client.ankihub_client in _se... View Issue
• ‼️ AnkiHubRequestException: AnkiHub request exception: HTTPSConnectionPool(host='app.ankihub.net', port=443): Max retries exc... 1322529746.ankihub_client.ankihub_client in _se... View Issue
• ‼️ AnkiHubRequestException: AnkiHub request exception: HTTPSConnectionPool(host='app.ankihub.net', port=443): Max retries exc... 1322529746.ankihub_client.ankihub_client in _se... View Issue

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