Basis Errors and Solutions

Adapter Framework Scheduler may fail to remove a job

July 10, 2009 at 5:44 am

[adapter] [File] [Framework] [JDBC] [Mail] [not] [overload] [polling] [scheduler] [scheduler proxy] [scheduler.exe] [task scheduler]

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Symptom

XI Adapter Framework’s scheduler may fail to remove the scheduled job. When this problem occurs, the affected job may get executed continuously for some period in parallel.
This problem can be suspected when some scheduled job gets executed unexpectedly frequently while others do not get executed.
This scheduler is used by various services of the Adapter Framework, such as the polling sender adapter services (File, JDBC, Mail, etc) and the channel administration service. When this problem occurs and the scheduler fails to remove one sender channel job, the polling action of this channel may be repeatedly executed in a very short period of time until this condition dissolves. In some cases, this problem may overload the system with many concurrently executing threads.

Other terms

Adapter Framework, Scheduler, not polling, File, JDBC ,Mail ,overload

Reason and Prerequisites

Program error
The scheduler used the hashcode operation to order two schedule jobs with the same next execution time. This could potentially result in a collision of two distinct schedule job objects.
It is noted that this problem could occur very rarely, namely when two scheduling jobs with the some object hash values were scheduled exactly at the same millisecond.
In some JVMs, particularly of those 64-bit VM with a large heap size,, this problem may occur more easily than in others, as they tend to generate hash values that can collide.

Solution

This problem has been fixed in this patch by not using an arithemetic operation that results in an underflow.
This patch resolves the issue by using an additional information to maintain the order of scheduled jobs.
Import the appropriate archive for SAP Exchange Infrastructure XI. The archives and the support package stack guide can be found on the SAP service Marketplace as described in SAP Note 952402.