Friday, 9 February 2018

DBG_21699 : Waiting for consumer to free buffer block

This is a very common warning message in informatica session log.

READER_1_1_1> DBG_21699 The reader is waiting for the DTM to provide buffer blocks. To improve session performance and to prevent the session from hanging, increase the DTM buffer pool size in the session properties.


In PowerCenter, each Reader (Source) transformation has an associated minimum number of free blocks required to continue processing.
When the actual number of free blocks is less than the minimum number, the following message is printed and a wait-notify mechanism is registered:

DBG_21699 Waiting for consumer to free buffer block​


The purpose of the wait is to ensure that one transformation does not dominate DTM buffer block usage in situations where the performance of transformation varies widely. For example, when the Reader is extremely fast and Writer is slow.

The minimum number of free blocks required by each Reader depends on several factors as follows:
  • Type of the Source (Relational, Flat File, Hierarchical)
  • The number of Sources Groups.
  • The total number of blocks in the session.
  • The actual value is calculated during run time and varies between limits 2 and 20.
The message could be ignored if the performance of the session is acceptable and there is no requirement to improve the session's performance.
If not, increasing the DTM Buffer size is the straightforward way to decrease the occurrence of this message.

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