IBM BPM, V8.0.1, All platforms > Administer the IT infrastructure > Manage events

Manage locks on sequenced events

The lock manager handles event sequencing locks. You can use the esAdmin command to list, delete, or unlock any lock in the lock manager.

The lock manager supports two operations on event locks:

• Lock: The lock operation attempts to acquire a lock and stores the lock request in a database. After a lock is granted, processing resumes for the invocation that requested the lock.
• Unlock: The unlock operation releases the current lock and grants the lock to the next lock request.

Requests for the same lock are put into a queue in the order in which they are received. Locks are persisted to the default IBM BPM database and data source to ensure they can be recovered in the case of a server failure.

The esAdmin command enables you to administer the active and queued locks currently in the lock manager. The following sections provide more detail on using esAdmin.

If you are using partitioned databases, run the esAdmin command once for each deployment target. In a clustered environment, you can run it on any cluster, but do not run it on the dmgr.

Listing locks

The esAdmin command can list all active and queued locks in the lock manager, or only those locks associated with a specific module, component, or method.

Use one of the following methods with esAdmin:

• listAll: Lists all active and queued locks in the lock manager.
• listLocks: Lists a subset of the active and queued locks in the lock manager. Specify one or more of the following parameters to return a filtered list of locks:
  • moduleName
  • componentName
  • methodName

  For example, the following command returns a list of active and queued locks for the CustComp component that is part of the CusMod module.

  esAdmin listLocks CustMod CustComp

The command returns output that looks like the following:

Sample output from esAdmin listLocks command

Lock Id	Sequence Id	Owner Id	Module	Component	Method	System Message Id
7564504	2	695376	CustMod	CustComp	createCust	A09- 427BE_5002
7564504	3	232757	CustMod	CustComp	createCust	ADF- 053RT_5004

In the output in Table 1, the sequence ID is the order in which the lock requests are queued; the lowest number in the sequence currently holds the lock. The system message ID specifies the ID for the corresponding service integration bus message; you can use this information to correlate lock requests with the messages on the destinations.

Releasing locks

Use the esAdmin command to release a single lock, as follows:

esAdmin unlock  lockId.

lockId is the unique lock ID returned by the esAdmin listLock or esAdmin listAll command.

This command is useful when you encounter a deadlock; you can release the lock that is deadlocked and grant it to the next lock request in the queue.

Delete locks

If you need to delete one or more locks, first stop the module associated with the lock. Then, use the esAdmin command to delete the lock from the database.

For examples:

esAdmin deleteLocks  moduleName

You must restart the module in order for the destinations to resume processing event messages.

Use the esAdmin deleteLocks command with caution. All locks in the specified module are deleted from the lock manager database.

Manage events