org.activiti.engine.impl.jobexecutor

Class LockFreeJobExecutor

java.lang.Object

org.activiti.engine.impl.jobexecutor.JobExecutor

org.activiti.engine.impl.jobexecutor.LockFreeJobExecutor

public class LockFreeJobExecutor
extends JobExecutor

JobExecutor, the next generation.

Author:

Joram Barrez

Field Summary

Fields

Modifier and Type	Field and Description
protected int	corePoolSize The minimal number of threads that are kept alive in the threadpool for job execution
protected Set<String>	currentlyProcessedJobs Used to avoid putting the same job twice on the queue
protected int	jobFetchBatchSize The number of jobs fetched in one query after they are already acquired
protected long	keepAliveTime The time (in milliseconds) a thread used for job execution must be kept alive before it is destroyed.
protected LockFreeAcquireJobsRunnable	lockFreeAcquireJobsRunnable The runnable responsible for fetching the jobs and put on the queue
protected int	maxPoolSize The maximum number of threads that are kept alive in the threadpool for job execution
protected int	queueSize The size of the queue on which jobs to be executed are placed
protected Map<String,JobEntity>	recentlyRemovedJobs When a job is removed from the currentlyProcessedJobs (in the ExecuteJobsRunnable), there can be a slight window of overlap: the jobs are already fetched in memory, but the removal happened just before.
protected long	secondsToWaitOnShutdown The time (in seconds) that is waited to gracefully shut down the threadpool used for job execution
protected ThreadPoolExecutor	threadPoolExecutor The thread pool used for job execution
protected BlockingQueue<Runnable>	threadPoolQueue The queue used for job execution work

Fields inherited from class org.activiti.engine.impl.jobexecutor.JobExecutor

acquireJobsCmd, acquireJobsRunnable, clockReader, commandExecutor, isActive, isAutoActivate, jobAcquisitionThread, lockOwner, lockTimeInMillis, maxJobsPerAcquisition, name, rejectedJobsHandler, waitTimeInMillis

Constructor Summary

Constructors

Constructor and Description
LockFreeJobExecutor()

Method Summary

Methods

Modifier and Type	Method and Description
void	executeJobs(List<String> jobIds)
int	getCorePoolSize()
Set<String>	getCurrentlyProcessedJobs()
int	getJobFetchBatchSize()
long	getKeepAliveTime()
int	getMaxPoolSize()
int	getQueueSize()
Map<String,JobEntity>	getRecentlyRemovedJobs()
long	getSecondsToWaitOnShutdown()
ThreadPoolExecutor	getThreadPoolExecutor()
BlockingQueue<Runnable>	getThreadPoolQueue()
protected void	initCurrentlyProcessedDataStructures()
boolean	isJobScheduledForExecution(JobEntity job)
void	jobDone(JobEntity job)
void	jobScheduledForExecution(JobEntity job)
void	setCorePoolSize(int corePoolSize)
void	setCurrentlyProcessedJobs(Set<String> currentlyProcessedJobs)
void	setJobFetchBatchSize(int jobFetchBatchSize)
void	setKeepAliveTime(long keepAliveTime)
void	setMaxPoolSize(int maxPoolSize)
void	setQueueSize(int queueSize)
void	setRecentlyRemovedJobs(Map<String,JobEntity> recentlyRemovedJobs)
void	setSecondsToWaitOnShutdown(long secondsToWaitOnShutdown)
void	setThreadPoolExecutor(ThreadPoolExecutor threadPoolExecutor)
void	setThreadPoolQueue(BlockingQueue<Runnable> threadPoolQueue)
protected void	startExecutingJobs()
protected void	startJobAcquisitionThread() Starts the acquisition thread
protected void	stopExecutingJobs()

Methods inherited from class org.activiti.engine.impl.jobexecutor.JobExecutor

ensureCleanup, ensureInitialization, getAcquireJobsCmd, getAcquireJobsRunnable, getCommandExecutor, getCurrentTime, getLockOwner, getLockTimeInMillis, getMaxJobsPerAcquisition, getName, getRejectedJobsHandler, getWaitTimeInMillis, isActive, isAutoActivate, jobDone, jobWasAdded, setAcquireJobsCmd, setAcquireJobsRunnable, setAutoActivate, setClockReader, setCommandExecutor, setLockOwner, setLockTimeInMillis, setMaxJobsPerAcquisition, setRejectedJobsHandler, setWaitTimeInMillis, shutdown, start, stopJobAcquisitionThread

Methods inherited from class java.lang.Object

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

Field Detail

corePoolSize

protected int corePoolSize

The minimal number of threads that are kept alive in the threadpool for job execution

maxPoolSize

protected int maxPoolSize

The maximum number of threads that are kept alive in the threadpool for job execution

keepAliveTime

protected long keepAliveTime

The time (in milliseconds) a thread used for job execution must be kept alive before it is destroyed. Default setting is 0. Having a non-default setting of 0 takes resources, but in the case of many job executions it avoids creating new threads all the time.

currentlyProcessedJobs

protected Set<String> currentlyProcessedJobs

Used to avoid putting the same job twice on the queue

recentlyRemovedJobs

protected Map<String,JobEntity> recentlyRemovedJobs

When a job is removed from the currentlyProcessedJobs (in the ExecuteJobsRunnable), there can be a slight window of overlap: the jobs are already fetched in memory, but the removal happened just before. At that point, the acquirement logic will try to put them on the queue again (because they were read from the database AND not found in the 'currentlyProcessedJobs' set, hence they are thought to be real, unprocessed jobs). To solve this, we keep a LRU cache of the last deleted entries. The size of this cache is equal to the 'currentlyProcessedJobs' size or the jobFetchBatchSize (the largest one of the two). Making it larger has no point, as with this size the window of overlap is covered

queueSize

protected int queueSize

The size of the queue on which jobs to be executed are placed

jobFetchBatchSize

protected int jobFetchBatchSize

The number of jobs fetched in one query after they are already acquired

threadPoolQueue

protected BlockingQueue<Runnable> threadPoolQueue

The queue used for job execution work

threadPoolExecutor

protected ThreadPoolExecutor threadPoolExecutor

The thread pool used for job execution

secondsToWaitOnShutdown

protected long secondsToWaitOnShutdown

The time (in seconds) that is waited to gracefully shut down the threadpool used for job execution

lockFreeAcquireJobsRunnable

protected LockFreeAcquireJobsRunnable lockFreeAcquireJobsRunnable

The runnable responsible for fetching the jobs and put on the queue

Constructor Detail

LockFreeJobExecutor

public LockFreeJobExecutor()

Method Detail

startExecutingJobs

protected void startExecutingJobs()

Specified by:

startExecutingJobs in class JobExecutor

stopExecutingJobs

protected void stopExecutingJobs()

Specified by:

stopExecutingJobs in class JobExecutor

executeJobs

public void executeJobs(List<String> jobIds)

Specified by:

executeJobs in class JobExecutor

startJobAcquisitionThread

protected void startJobAcquisitionThread()

Description copied from class: JobExecutor

Starts the acquisition thread

Overrides:

startJobAcquisitionThread in class JobExecutor

initCurrentlyProcessedDataStructures

protected void initCurrentlyProcessedDataStructures()

jobScheduledForExecution

public void jobScheduledForExecution(JobEntity job)

isJobScheduledForExecution

public boolean isJobScheduledForExecution(JobEntity job)

jobDone

public void jobDone(JobEntity job)

Overrides:

jobDone in class JobExecutor

getQueueSize

public int getQueueSize()

setQueueSize

public void setQueueSize(int queueSize)

getCorePoolSize

public int getCorePoolSize()

setCorePoolSize

public void setCorePoolSize(int corePoolSize)

getMaxPoolSize

public int getMaxPoolSize()

setMaxPoolSize

public void setMaxPoolSize(int maxPoolSize)

getKeepAliveTime

public long getKeepAliveTime()

setKeepAliveTime

public void setKeepAliveTime(long keepAliveTime)

getSecondsToWaitOnShutdown

public long getSecondsToWaitOnShutdown()

setSecondsToWaitOnShutdown

public void setSecondsToWaitOnShutdown(long secondsToWaitOnShutdown)

getThreadPoolQueue

public BlockingQueue<Runnable> getThreadPoolQueue()

setThreadPoolQueue

public void setThreadPoolQueue(BlockingQueue<Runnable> threadPoolQueue)

getThreadPoolExecutor

public ThreadPoolExecutor getThreadPoolExecutor()

setThreadPoolExecutor

public void setThreadPoolExecutor(ThreadPoolExecutor threadPoolExecutor)

getJobFetchBatchSize

public int getJobFetchBatchSize()

setJobFetchBatchSize

public void setJobFetchBatchSize(int jobFetchBatchSize)

getCurrentlyProcessedJobs

public Set<String> getCurrentlyProcessedJobs()

setCurrentlyProcessedJobs

public void setCurrentlyProcessedJobs(Set<String> currentlyProcessedJobs)

getRecentlyRemovedJobs

public Map<String,JobEntity> getRecentlyRemovedJobs()

setRecentlyRemovedJobs

public void setRecentlyRemovedJobs(Map<String,JobEntity> recentlyRemovedJobs)