Package org.apache.hadoop.util

Class JvmPauseMonitor

java.lang.Object
org.apache.hadoop.service.AbstractService
org.apache.hadoop.util.JvmPauseMonitor
All Implemented Interfaces:
Closeable, AutoCloseable, Service
@Private public class JvmPauseMonitor extends AbstractService
Class which sets up a simple thread which runs in a loop sleeping for a short interval of time. If the sleep takes significantly longer than its target time, it implies that the JVM or host machine has paused processing, which may cause other problems. If such a pause is detected, the thread logs a message.

  • Constructor Details

    • JvmPauseMonitor

      public JvmPauseMonitor()

  • Method Details

    • serviceInit

      protected void serviceInit(Configuration conf) throws Exception
      Description copied from class: AbstractService
      All initialization code needed by a service. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.init(Configuration) prevents re-entrancy. The base implementation checks to see if the subclass has created a new configuration instance, and if so, updates the base class value
      Overrides:
      serviceInit in class AbstractService
      Parameters:
      conf - configuration
      Throws:
      Exception - on a failure -these will be caught, possibly wrapped, and will trigger a service stop

    • serviceStart

      protected void serviceStart() throws Exception
      Description copied from class: AbstractService
      Actions called during the INITED to STARTED transition. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.start() prevents re-entrancy.
      Overrides:
      serviceStart in class AbstractService
      Throws:
      Exception - if needed -these will be caught, wrapped, and trigger a service stop

    • serviceStop

      protected void serviceStop() throws Exception
      Description copied from class: AbstractService
      Actions called during the transition to the STOPPED state. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.stop() prevents re-entrancy. Implementations MUST write this to be robust against failures, including checks for null references -and for the first failure to not stop other attempts to shut down parts of the service.
      Overrides:
      serviceStop in class AbstractService
      Throws:
      Exception - if needed -these will be caught and logged.

    • isStarted

      public boolean isStarted()

    • getNumGcWarnThresholdExceeded

      public long getNumGcWarnThresholdExceeded()

    • getNumGcInfoThresholdExceeded

      public long getNumGcInfoThresholdExceeded()

    • getTotalGcExtraSleepTime

      public long getTotalGcExtraSleepTime()

    • main

      public static void main(String[] args) throws Exception
      Simple 'main' to facilitate manual testing of the pause monitor. This main function just leaks memory into a list. Running this class with a 1GB heap will very quickly go into "GC hell" and result in log messages about the GC pauses.
      Parameters:
      args - args.
      Throws:
      Exception - Exception.