[BUG]: keep track of current span if task must be queued

[codetheweb]

Description of changes

When a task is dispatched and there's no available worker thread the task is put into a queue. We weren't holding the current span at time of task creation in the queue, leading to mysteriously missing span trees. This was especially apparent under high concurrent load or when the configuration specified a low number of worker threads.

Test plan

How are these changes tested?

Verified that formerly missing spans now show up in Jaeger, especially when num_worker_threads is 1.

Documentation Changes

Are all docstrings for user-facing APIs updated if required? Do we need to make documentation changes in the docs repository?

n/a

[github-actions]

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Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
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• If appropriate, are there adequate property based tests?
• If appropriate, are there adequate unit tests?
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• Are error messages user-friendly?
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System Compatibility

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Quality

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