We have two places we build up strings for WiredTiger config based on checks in MongoDB:

• The WiredTiger cursor constructor
• The WiredTigerBeginTxnBlock constructor

These have an outsized impact on workloads, accounting for example 8% of all allocations in mixed_genny_workloads_rate_limited.

It seems possible here to either have a pre-allocated buffer, or even something really dumb like a separate static string for each configuration enumeration if the underlying WiredTiger code doesn't need to modify the string.

This seems like a low amount of effort to potentially positively affect the performance of high-value workloads.

Reach out for details on how to see the heap analysis information.