Config & env#

Quick reference for the knobs that influence logging behavior. Defaults match the source in logging.rs.

Knobs#

Knob	Type & default	How to set	When it takes effect	Affects	Notes
`HYPERACTOR_READ_LOG_BUFFER` ↯	`usize`, default 100	Environment variable (process env)	Read when stream forwarders are started	Stream forwarder read/batch behavior	Upper bound on lines read before a forced flush/resume cycle. Useful to bound memory when a child is chatty.
`HYPERACTOR_FORCE_FILE_LOG`	`bool`, default false	Environment variable	Read when `FileAppender::new()` runs	Local file aggregation	If true, create per-proc stdout/stderr files even in `Env::Local`. If false in `Env::Local`, file aggregation is skipped.
`HYPERACTOR_PREFIX_WITH_RANK`	`bool`, default true	Environment variable	Read when `StreamFwder::start(...)` wires a stream	Line formatting in the bootstrap process	Prepends `"[{rank}] "` to each line before shipping/teeing. Toggle requires re-wiring the forwarders to take effect.
`DEFAULT_AGGREGATE_WINDOW_SEC`	`u64`, default 5	Compile-time constant; can be overridden at runtime via Python `set_mode(..., aggregate_window_sec=…)`	Runtime (client actor)	Client aggregation window	If `None`, aggregation is disabled and lines print immediately. When switching from `Some`→`None`, pending aggregates are flushed first.
`MAX_LINE_SIZE`	`usize`, default *4 1024**	Compile-time constant	Always on	Line truncation in stream forwarder	Lines longer than 4 KiB are truncated and suffixed with `"… [TRUNCATED]"` before reaching the client.

↯ Defined as the READ_LOG_BUFFER attr in code (maps to env HYPERACTOR_READ_LOG_BUFFER).

Runtime-adjustable: aggregation window (via Python LoggingMeshClient.set_mode(..., aggregate_window_sec=…)).
Apply on (re)start/wiring: HYPERACTOR_FORCE_FILE_LOG, HYPERACTOR_PREFIX_WITH_RANK, HYPERACTOR_READ_LOG_BUFFER — changing these requires recreating the corresponding forwarders/file appenders to take effect.
Fixed at build time: MAX_LINE_SIZE, the default value of DEFAULT_AGGREGATE_WINDOW_SEC (you can still override the window at runtime via Python).