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also get performance benefits from enabling this system variable, because they use the same locking mechanisms as the replicas. 

• replication_sender_observe_commit_only 

<img src='content_image/784752.jpg'>

Limit callbacks to improve performance for semisynchronous replication. This setting and replication_optimize_for_static_plugin_config  help as the number of replicas increases, because contention for locks can slow down performance. 

This system variable can be enabled before or after installing the semisynchronous replication plugin, and can be enabled while replication is running. Semisynchronous replication source servers can also get performance benefits from enabling this system variable, because they use the same locking mechanisms as the replicas. 

• report_host 

<img src='content_image/784753.jpg'>

The host name or IP address of the replica to be reported to the source during replica registration. This value appears in the output of SHOW REPLICAS | SHOW SLAVE HOSTS  on the source server. Leave the value unset if you do not want the replica to register itself with the source. 

<img src='content_image/784757.jpg'>

• report_password 

## Note 

It is not sufficient for the source to simply read the IP address of the replica server from the TCP/IP socket after the replica connects. Due to NAT and other routing issues, that IP may not be valid for connecting to the replica from the source or other hosts. 

<img src='content_image/784754.jpg'>

