Package org.camunda.bpm.engine.impl.jobexecutor

Class BackoffJobAcquisitionStrategy

java.lang.Object
org.camunda.bpm.engine.impl.jobexecutor.BackoffJobAcquisitionStrategy
All Implemented Interfaces:
JobAcquisitionStrategy
public class BackoffJobAcquisitionStrategy extends Object implements JobAcquisitionStrategy

Determines the number of jobs to acquire and the time to wait between acquisition cycles by an exponential backoff strategy.

Manages two kinds of backoff times:

  • idle time: Wait for a certain amount of time when no jobs are available
  • backoff time: Wait for a certain amount of time when jobs are available but could not successfully be acquired
Both times are calculated by applying an exponential backoff. This means, when the respective conditions repeatedly hold, the time increases exponentially from one acquisition cycle to the next.

This implementation manages idle and backoff time in terms of levels. The initial backoff level is 0, meaning that no backoff is applied. In case the condition for increasing backoff applies, the backoff level is incremented. The actual time to wait is then computed as follows 

timeToWait = baseBackoffTime * (backoffFactor ^ (backoffLevel - 1))

Accordingly, the maximum possible backoff level is 

maximumLevel = floor( log( backoffFactor, maximumBackoffTime / baseBackoffTime) ) + 1
(where log(a, b) is the logarithm of b to the base of a)
Author:
Thorben Lindhauer

  • Field Details

    • DEFAULT_EXECUTION_SATURATION_WAIT_TIME

      public static long DEFAULT_EXECUTION_SATURATION_WAIT_TIME

    • baseIdleWaitTime

      protected long baseIdleWaitTime

    • idleIncreaseFactor

      protected float idleIncreaseFactor

    • idleLevel

      protected int idleLevel

    • maxIdleLevel

      protected int maxIdleLevel

    • maxIdleWaitTime

      protected long maxIdleWaitTime

    • baseBackoffWaitTime

      protected long baseBackoffWaitTime

    • backoffIncreaseFactor

      protected float backoffIncreaseFactor

    • backoffLevel

      protected int backoffLevel

    • maxBackoffLevel

      protected int maxBackoffLevel

    • maxBackoffWaitTime

      protected long maxBackoffWaitTime

    • applyJitter

      protected boolean applyJitter

    • numAcquisitionsWithoutLockingFailure

      protected int numAcquisitionsWithoutLockingFailure

    • backoffDecreaseThreshold

      protected int backoffDecreaseThreshold

    • baseNumJobsToAcquire

      protected int baseNumJobsToAcquire

    • jobsToAcquire

      protected Map<String,Integer> jobsToAcquire

    • executionSaturated

      protected boolean executionSaturated

    • executionSaturationWaitTime

      protected long executionSaturationWaitTime

  • Constructor Details

    • BackoffJobAcquisitionStrategy

      public BackoffJobAcquisitionStrategy(long baseIdleWaitTime, float idleIncreaseFactor, long maxIdleTime, long baseBackoffWaitTime, float backoffIncreaseFactor, long maxBackoffTime, int backoffDecreaseThreshold, int baseNumJobsToAcquire)

    • BackoffJobAcquisitionStrategy

      public BackoffJobAcquisitionStrategy(JobExecutor jobExecutor)

  • Method Details

    • initializeMaxLevels

      protected void initializeMaxLevels()

    • log

      protected double log(double base, double value)

    • reconfigure

      public void reconfigure(JobAcquisitionContext context)
      Specified by:
      reconfigure in interface JobAcquisitionStrategy

    • allSubmittedJobsRejected

      protected boolean allSubmittedJobsRejected(JobAcquisitionContext context)
      Returns:
      true, if all acquired jobs (spanning all engines) were rejected for execution

    • reconfigureIdleLevel

      protected void reconfigureIdleLevel(JobAcquisitionContext context)

    • reconfigureBackoffLevel

      protected void reconfigureBackoffLevel(JobAcquisitionContext context)

    • reconfigureNumberOfJobsToAcquire

      protected void reconfigureNumberOfJobsToAcquire(JobAcquisitionContext context)

    • getWaitTime

      public long getWaitTime()
      Specified by:
      getWaitTime in interface JobAcquisitionStrategy

    • calculateIdleTime

      protected long calculateIdleTime()

    • calculateBackoffTime

      protected long calculateBackoffTime()

    • getNumJobsToAcquire

      public int getNumJobsToAcquire(String processEngine)
      Specified by:
      getNumJobsToAcquire in interface JobAcquisitionStrategy