IBM BPM, V8.0.1, All platforms > Migrating and upgrading your IBM BPM environment > Migrating from other products > Migrating from WebSphere InterChange Server or WebSphere Business Integration Server Express > Premigration considerations
Premigration considerations: Preventing database collisions
Prevent database collisions from occurring by scheduling events to occur at least two seconds apart.
If your migrated applications cause multiple events to occur at the same time to WebSphere Business Integration components, this could cause database collisions, or deadlocks. These occur when the IBM BPM Application Scheduler (AppScheduler) schedules multiple events to occur at exactly the same time. When a deadlock occurs, the event that caused it is rolled back and attempted again as soon as possible. This cycle continues until each of the threads attempting to access the database successfully updates it.
For example:
AppScheduler E com.ibm.wbiserver.scheduler.AppSchedulerMB process CWLWS0021E: The AppSchedulerMB.process method has generated an exception. WSRdbXaResour E DSRA0304E: XAException occurred. XAException contents and details are: The DB2 Error message is : Error executing a XAResource.end(), Server returned XA_RBDEADLOCK The DB2 Error code is : -4203 The DB2 SQLState is : null
To prevent this from occurring, schedule the events to occur far enough apart so that deadlocks do not occur. IBM recommends that you schedule events to occur at least two seconds apart; however, the amount of time you need will vary depending on other factors in your environment that affect performance such as database size, hardware, connection speed and other factors.
