Dynamic namespace loading can cause race conditions

[levand]

Affected Component & Version: com.cognitect.aws/api 0.8.352

Problem Description

It is possible to invoke cognitect.aws.api/client concurrently, such that the dynamically generated call to require on line 78 (https://github.com/cognitect-labs/aws-api/blob/v0.8.352/src/cognitect/aws/client/api.clj#L78) is also invoked concurrently.

This permits a race condition where, if namespace loading goes just wrong, can result in spurious No such var compile exceptions on otherwise straightforward code in the dynamically loaded namespaces.

Proposed Solution

Ensure that the dynamic call to require cannot be called in parallel, e.g by wrapping it in a locking form.

Pre-patch workaround

Ensure that calling code does not invoke cognitect.aws.api/client in parallel.

[dchelimsky]

Fixed in 5f6fdbd. Will close after released.

[dchelimsky]

Thanks, as always, @levand, for the descriptive and actionable report.

[dchelimsky]

Released in 0.8.378.