Function recorder_from_env 

pub fn recorder_from_env() -> Result<(Recorder, Runtime), Error>

Available on crate feature dial9 only.

Build a recorder and its instrumented Tokio runtime from standard DIAL9_* environment variables.

Hand it straight to the macro: #[dial9::main(config = dial9::recorder_from_env)].

Per-process namespace isolation

On the disk path, segments are written to a per-process subdirectory {DIAL9_TRACE_DIR}/{boot_id}/, where boot_id is {4-alpha}-{pid} (e.g. qmxz-48291). This keeps processes that share a trace directory from reading and re-uploading each other’s segments. Each process holds an advisory flock on {boot_id}/.lock for its lifetime; on startup it reclaims any sibling namespace whose lock it can acquire (i.e. the owner has exited). Set DIAL9_GC_DEAD_NAMESPACES=false to keep prior runs’ directories instead. Handy locally when comparing traces across runs.

Supported local trace writer variables:

Variable	Default	Meaning
DIAL9_ENABLED	false	Master switch for installing telemetry.
DIAL9_TRACE_DIR	/tmp/dial9-traces	Directory for rotated trace segments.
DIAL9_ROTATION_SECS	60	Rotation period in seconds, measured monotonically from writer start.
DIAL9_MAX_DISK_USAGE_MB	1024	Total on-disk trace budget in MiB.
DIAL9_MAX_FILE_SIZE_MB	min(100, total / 4)	Per-file trace segment size in MiB.
DIAL9_GC_DEAD_NAMESPACES	true	Reclaim dead peers’ namespace dirs at startup.

Supported runtime variables:

Variable	Default	Meaning
DIAL9_TASK_TRACKING_ENABLED	true	Track tasks spawned through dial9 handles.
DIAL9_TOKIO_INSTRUMENTATION_ENABLED	true	Install dial9’s Tokio runtime hook instrumentation.
DIAL9_RUNTIME_NAME	unset	Human-readable runtime name in trace metadata.

Supported S3 variables (worker-s3 feature required):

Variable	Default	Meaning
DIAL9_S3_BUCKET	unset	Upload sealed trace segments to this bucket.
DIAL9_SERVICE_NAME	binary name	Service name used in S3 keys and metadata.
DIAL9_S3_PREFIX	dial9-traces	S3 object key prefix.

Supported CPU profiling variables (cpu-profiling feature required):

Variable	Default	Meaning
DIAL9_CPU_PROFILE_ENABLED	true on Linux with cpu-profiling, false otherwise	Enable CPU stack sampling.
DIAL9_CPU_SAMPLE_HZ	99	CPU sampling frequency in Hz.
DIAL9_SCHEDULE_PROFILE_ENABLED	true on Linux with cpu-profiling, false otherwise	Enable per-worker scheduler event capture. Requires the CPU profiling setup.

Supported memory profiling variables (memory-profiling feature required; applications must still install the Dial9Allocator from the memory module as their #[global_allocator]):

Variable	Default	Meaning
DIAL9_MEMORY_PROFILE_ENABLED	false	Enable memory allocation sampling.
DIAL9_MEMORY_SAMPLE_RATE_BYTES	524288	Mean bytes between sampled allocations.
DIAL9_MEMORY_TRACK_LIVESET	false	Track frees for leak detection.

Supported process resource usage variables (process-resource feature required):

Variable	Default	Meaning
DIAL9_PROCESS_RESOURCE_USAGE_ENABLED	true on Unix with process-resource, false otherwise	Enable process resource usage sampling from getrusage(RUSAGE_SELF).
DIAL9_PROCESS_RESOURCE_USAGE_SAMPLE_INTERVAL_MS	100	Sampling interval in milliseconds.

Supported socket accept queue variables (linux-socket feature required):

Variable	Default	Meaning
DIAL9_SOCKET_ACCEPT_QUEUES_ENABLED	false	Enable TCP accept queue snapshots from Linux sock_diag.
DIAL9_SOCKET_ACCEPT_QUEUES_SAMPLE_INTERVAL_MS	400	Sampling interval in milliseconds.

Supported task dump variables (capture requires the taskdump feature, --cfg tokio_unstable, Linux on aarch64, x86, or x86_64, and futures spawned through a Dial9 spawner, such as dial9::spawn):

Variable	Default	Meaning
DIAL9_TASK_DUMP_ENABLED	false	Capture async task dumps at idle yield points.
DIAL9_TASK_DUMP_IDLE_THRESHOLD_MS	10	Mean idle duration for task dump sampling.

See TaskDumpConfig for configuration details.

Missing variables use defaults. Blank, invalid, or non-Unicode values emit a warning and are treated as missing. With DIAL9_ENABLED off, or when the trace writer cannot be created, the returned recorder builds a plain Tokio runtime (the failure is logged at error!).

Errors

Only if the Tokio runtime cannot be built.