Replication ready size limit

You can tune the replication ready size limit by setting the IBMSLAPD_REPL_READY_SIZE_LIMIT environment variable. The replication ready size limit controls the queue size of the replication operations from the list of replication update entries.

The default size limit is 10. There is one queue per connection to a replica. Updates that are related, such as modifications or subentries of an entry, are placed in the same queue. If the queue size exceeds the set size limit, the main replication thread waits for the queue size to be lesser than the limit. When the queue size becomes lesser that the limit, it reduces the processor usage by the main replication thread to determine the dependencies between the updates. In test environment, the size of the queue was varied from one entry up to 200 entries. Although, an increase in raw throughput was not evident but processor usage was reduced at certain settings of this variable. The following graph shows that the throughput normalized to 100% of processor usage. In the test environment, the absolute throughput did not change. Bigger the replication ready size limit value in the graph, lesser processor usage for transactions per second. In this graph, a transaction is defined as a queued replication record (ldap_modify) that is sent to the supplier.