Fix data races in VersionManager #6411
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tgoyne
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bmunkholm
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Mar 23, 2023
CHANGELOG.md
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| ### Fixed | |||
| * `SyncSession::pause()` could hold a reference to the database open after shutting down the sync session, preventing users from being able to delete the realm. ([#6372](https://github.com/realm/realm-core/issues/6372), since v13.3.0) | |||
| * Fix a data race in `DB::VersionManager`. If one thread committed a write transaction which increased the number of live versions above the previous highest seen during the current session at the same time as another thread began a read, the reading thread could read from a no-longer-valid memory mapping ([PR #6411](https://github.com/realm/realm-core/pull/6411), since v13.0.0). | |||
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How could end users experience this? @tgoyne could this be rephrased in end user terms that could easily be put in the SDK release notes?
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It's a data race detected by tsan, not something we observed functional problems from. I have no idea what would happen when the race is hit other than that it'd be bad.
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Good to know, then maybe we should add. "This hasn't been reported by any users" or similar?
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Access to `m_info` was not guarded by a lock, so one thread could potentially remap it while another thread was reading from it.
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Access to
m_infowas not guarded by a lock, so one thread could potentially remap it while another thread was reading from it. TSan sometimes catches this running the Swift tests.