Module watchdog 

Watchdog timer for detecting stuck strands

Monitors strand execution time and triggers alerts when strands run too long without yielding. This helps detect infinite loops and runaway computation.

Configuration (Environment Variables)

Variable	Default	Description
SEQ_WATCHDOG_SECS	0 (disabled)	Threshold in seconds for “stuck” strand
SEQ_WATCHDOG_INTERVAL	5	Check frequency in seconds
SEQ_WATCHDOG_ACTION	warn	Action: warn (dump diagnostics) or exit (terminate)

Example

# Enable watchdog with 30 second threshold, check every 10 seconds
SEQ_WATCHDOG_SECS=30 SEQ_WATCHDOG_INTERVAL=10 ./my-program

# Enable watchdog that exits on stuck strand
SEQ_WATCHDOG_SECS=60 SEQ_WATCHDOG_ACTION=exit ./my-program

Design

The watchdog runs on a dedicated thread and periodically scans the strand registry. It compares each strand’s spawn time against the current time to detect strands that have been running longer than the threshold.

This piggybacks on the existing strand registry infrastructure, requiring no additional tracking overhead on the hot path.

Feature Flag

This module requires the diagnostics feature (enabled by default). When disabled, the watchdog is not compiled.

Structs

WatchdogConfig

Watchdog configuration

Enums

WatchdogAction

Action to take when watchdog detects a stuck strand

Functions

install_watchdog

Install the watchdog timer