Default SSL makes mysqlslap much slower, tests fail with timeout

Starting from this push in 10.10

Author: Sergei Golubchik

Date:   Mon May 23 12:43:22 2022 +0200

    MDEV-27105 --ssl option set as default for mariadb CLI

    but without server cert verification

some tests take many times longer, and almost inevitably fail with timeout. E.g. rocksdb.concurrent_alter fails on nearly every build/builder in buildbot, while before the change it was only taking a few seconds.

On my machine the ratio is not as big, but still very visible (it's the command that the test runs inside):

$ time $MYSQL_SLAP  --silent --delimiter=";" --query="select * from a1 where a=1" --concurrency=16 --iterations=1000

real	0m10.935s

user	0m9.951s

sys	0m3.147s

$ time $MYSQL_SLAP --skip-ssl --silent --delimiter=";" --query="select * from a1 where a=1" --concurrency=16 --iterations=1000

real	0m0.841s

user	0m0.457s

sys	0m2.026s

Probably there are other affected tests, the rocksdb is only most visible because it actually fails.

we probably need to change MTR default config to turn off SSL for mysqlslap, but first it needs to be confirmed that such a difference in default client performance is expected.