Summary

NewInsufficientBytesError creates a stack trace, which allocates a lot of memory. For some reason, this is called a lot during normal operations, particularly by the Elements function.

When ADL does format conversions, such as to Parquet, we recursively traverse documents and have observed trace memory allocations significantly greater than the underlying data traversed. This may be related to OOM problems we've seen in production. See attached pprof image.

Please provide the version of the driver. If applicable, please provide the MongoDB server version and topology (standalone, replica set, or sharded cluster).

1.9.0

How to Reproduce

Traverse a large amount of BSON documents with Elements and look at memory allocations with the profiler.

Additional Background

The stack trace appears to have been introduced in the original codebase. The function to retrieve it, ErrorStack, does not appear to be used in the codebase. Because bsoncore is under bsonx, it should be safe to remove the stack trace functionality as it doesn't affect external, stable APIs.