fix(NODE-6394): pause message stream when not listening for events

[baileympearson]

Description

What is changing?

The message stream is paused when we're not reading from it, so we do not miss data events.

Is there new documentation needed for these changes?

What is the motivation for this change?

Release Highlight

Fixed indefinite hang bug for high write load scenarios

When performing large and many write operations, the driver will likely encounter buffering at the socket layer. The logic that waited until buffered writes were complete would mistakenly drop 'data' (reading from the socket), causing the driver to hang indefinitely or until a socket timeout. Using pausing and resuming mechanisms exposed by Node streams we have eliminated the possibility for data events to go unhandled.

Shout out to @hunkydoryrepair for debugging and finding this issue!

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
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• Changes are covered by tests
• New TODOs have a related JIRA ticket

[nbbeeken]

Failures unrelated

[hunkydoryrepair]

any chance of a patch release until 6.10 is out? Maybe a 6.9.1? Especially since 6.10 removes mongo 3.6 support, some won't have option to upgrade.

[alexbevi]

Based on the MongoDB Software Lifecycle Schedules MongoDB 3.6 reached EOL in April 2021.

It's unlikely there'd be enough demand to support this server version to act as a forcing function for a patch release.

[hunkydoryrepair]

Fair enough. we are stuck on 6.3 since this has been broken for a while and would love to be able to use the optimizations done since then.