zcashd/doc/release-notes.md

(note: this is a temporary file, to be added-to by anybody, and moved to release-notes at release time)

Notable changes

New logging system

The zcashd logging system is now powered by the Rust tracing crate. This has two main benefits:

• tracing supports the concept of "spans", which represent periods of time with a beginning and end. These enable logging additional information about temporality and causality of events. (Regular log lines, which represent moments in time, are called events in tracing.)
• Spans and events are structured, and can record typed data in addition to text messages. This structure can then be filtered dynamically.

The existing -debug=target config flags are mapped to tracing log filters, and will continue to correctly enable additional logging when starting zcashd. A new setlogfilter RPC method has been introduced that enables reconfiguring the log filter at runtime. See zcash-cli help setlogfilter for its syntax.

As a minor note, zcashd no longer reopens the debug.log file on SIGHUP. This behaviour was originally introduced in upstream Bitcoin Core to support log rotation using external tools. tracing supports log rotation internally (which is currently disabled), as well as a variety of interesting backends (such as journald and OpenTelemetry integration); we are investigating how these might be exposed in future releases.