MySql 5.6 multithreaded slave performance issue

MySQL & MariaDB Other MySQL® Questions
1

Hi,

We are testing MySql 5.6 replication multithread slave feature in local environment. We have observed that negative performance results. Test case details as follows:

Case 1:

  1. Setup the Master/Slave replication with 3 databases with one table (db import, slave setup etc…)
  2. stop the slave and in master update the 10K records in each table in each database parallelly
  3. Once the updates are done in master, start the slave with single thread
  4. Time taken to update the data in slave is 53 sec

Case 2:

  1. Setup the Master/Slave replication with 3 databases with one table (db import, slave setup etc…)
  2. stop the slave and in master update the 10K records in each table in each database parallelly
  3. Once the updates are done in master, start the slave with 3 worker threads
  4. Time taken to update the data in slave is 109 sec

We are expected that case2 should take less time than case 1 but results are different.
We have tried above test cases numerous iterations but found negative results.
Note: In Case1 and Case2 all configs are same except multiple worker threads.

Thank you in advance.