net.i2p.router.tasks

Class RouterWatchdog

java.lang.Object

net.i2p.router.tasks.RouterWatchdog

All Implemented Interfaces:

Runnable

public class RouterWatchdog
extends Object
implements Runnable

Router health monitor and automatic recovery system. This watchdog runs continuously to monitor router health and detect potentially hung or unresponsive states. It checks various system components including job queue processing, client responsiveness, and network connectivity. Monitoring Checks:

• Job queue liveliness - detects stuck jobs
• Client manager responsiveness - ensures clients are alive
• Network error rates - detects connectivity issues
• Communication system status - checks network health

Recovery Actions:

• Logs detailed system status when problems detected
• Generates thread dumps for debugging hung states
• May force JVM restart after consecutive failures
• Configurable via watchdog.haltOnHang property

The watchdog runs every minute and will attempt recovery if problems persist across multiple consecutive checks. This helps prevent router from becoming completely unresponsive and ensures automatic recovery from transient issues.

Constructor Summary

Constructors

Constructor and Description
RouterWatchdog(RouterContext ctx) Create a new router watchdog.

Method Summary

Modifier and Type	Method and Description
void	monitorRouter() Monitor router health and take action if needed.
void	run() Main watchdog monitoring loop.
void	shutdown() Shutdown the watchdog gracefully.
boolean	verifyClientLiveliness() Verify that client applications are responsive.
boolean	verifyJobQueueLiveliness() Verify that the job queue is processing jobs normally.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RouterWatchdog

public RouterWatchdog(RouterContext ctx)

Create a new router watchdog. The watchdog monitors router health and can force a restart if the router appears to be hung or unresponsive.

Parameters:

ctx - the router context for accessing router services and logging

Method Detail

monitorRouter

public void monitorRouter()

Monitor router health and take action if needed. Checks job queue liveliness, client responsiveness, and network status. If problems are detected, logs status and may force a restart after consecutive failures.

run

public void run()

Main watchdog monitoring loop. Runs continuously while the watchdog is active, checking router health every minute and taking action if problems are detected.

Specified by:

run in interface Runnable

shutdown

public void shutdown()

Shutdown the watchdog gracefully. Sets the running flag to false to stop the monitoring loop.

verifyClientLiveliness

public boolean verifyClientLiveliness()

Verify that client applications are responsive. Delegates to the client manager to check if all client applications are still responding properly.

Returns:

true if all clients appear healthy, false otherwise

verifyJobQueueLiveliness

public boolean verifyJobQueueLiveliness()

Verify that the job queue is processing jobs normally. Checks if any job has been running for too long, which could indicate a hung job queue.

Returns:

true if job queue appears healthy, false if a job has been running longer than the maximum allowed time