Summary

Currently some Go Driver GridFS API methods are not goroutine-safe. While we don't explicitly document that the GridFS API is goroutine safe, it's surprising to users because the Go Driver CRUD API is goroutine-safe and there's no technical reason that the GridFS API shouldn't be goroutine-safe.

In the best case, like what happened in GODRIVER-3841, users detect that the GridFS methods are not goroutine-safe and use them strictly serially. In the worst case, users call the GridFS methods concurrently and nothing bad happens most of the time, but it causes intermittent errors, possibly data corruption (although we haven't directly observed data corruption).

Motivation

Who is the affected end user?

Developers using the Go Driver to build applications that use the GridFS API.

How does this affect the end user?

They either see Go data race detector test failures, or they experience intermittent errors. There's a possibility of data corruption, but it hasn't directly been observed.

How likely is it that this problem or use case will occur?

Currently the problem happens when multiple concurrent upload requests try to create the GridFS collections and indexes, which is guarded in the Go Driver with a non-atomically-accessed boolean. The probability of that happening depends on the call pattern, but it's relatively low.

The probability of users detecting the issue with the Go data race detector is much higher.

If the problem does occur, what are the consequences and how severe are they?

• Go data race detector failures in tests
• Intermittent errors returned by the GridFS API
• Possibly data corruption, although that's never been observed.

Is this issue urgent?

No. We don't guarantee that the GridFS API is goroutine-safe, although it's reasonable to assume that it is. We've received one recent user report about lack of goroutine safety.

Is this ticket required by a downstream team?

No.

Is this ticket only for tests?

No.

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