The current story around logging within signal handlers is not very ergonomic from either the developer's or the debugger's perspective. There isn't a good way to produce log messages that leverage the strengths of structured logging. The logging that occurs in signal handlers has to use malloc-free tooling to avoid allocating memory during signal handlers, which is dangerous as documented in SERVER-82658. We don't have any support on top of that malloc-free tooling to build JSON objects and emit them as fields. Rather, we only have the coarse-grained support for setting the message field as a string. This results in awkward constructions, like emitting a JSON-like object, stringified, in the message field.

Revisit the logging support in the signal handling code, and see if we can add support for emitting log statements with structured contents.