Optimizing MySQL 5.6 for unit tests

Question

We have a MySQL instance for unit tests. Our unit tests work very heavily on MySQL. Therefore, we put /var/lib/mysql dir in tmpfs file system because we don't need persistent data in unit tests.

Our performance peaked when we did this; however, I would like to consult with you what's the best configuration for MySQL in this case.

It's very common to put MySQL in tmpfs (memory) and run non-important stuff like unit tests. The question is: What's best configuration for InnoDB to run in tmpfs?

These are the configs we have in my.cnf:

max_connections=350
innodb_fast_shutdown=2
innodb_log_file_size=1048576
innodb_doublewrite=0
innodb_flush_method=O_DIRECT

All our databases are in InnoDB. We don't mind losing some of the data.

P.S. You might ask at this point, why not MEMORY engine? That's because MEMORY has table-level locking only, and part of our unit tests are based on this.

EDIT: We've finished this project, we based our configuration from this blogpost: http://jotschi.de/2014/02/03/high-performance-mysql-testdatabase/

Answer 1

the innodb_log_file_size looks rather small for what I assume is bulk loaded unit test data with lots of writes.

A decent innodb_buffer_pool_size needs to be set that accounts for the active test size.

Because crash safety isn't a concern, like innodb_doublewrite=0 innodb_flush_log_at_trx_commit=0, will speed up write transactions.

max_connections implies you are doing multithreaded clients and if those are connecting/disconnecting maybe set thread_cache_size to the maximum number typically used.

A SHOW GLOBAL STATUS after a test run might give a hint as to what other aspects could be tuned.