LogRecord Attributes - preallocate attributes vec?

[cijothomas]

Since we don't pre-allocate, the vec starts with size 1, and often requires re-allocating. Would we start with a default size of, say 5? (don't ask me why 5, just a magic number!)

Opening an issue to track this improvement. The change can improve current throughput, benchmark by 10-20% (as they all need ~5 attributes.)

[lalitb]

Thanks, let's track this potential improvement with benchmark of both memory and throughput while handling this.

[cijothomas]

From 7/2 SIG meeting: Start with default = 8. In future, we can make it configurable, if we chose to and there is demand.

[lalitb]

I think we discussed it earlier - If we plan to start with default size, we can also evaluate using smallvec, to allocate this initial capacity on stack. tokio-tracing is doing something similar for the metrics attributes.