>>>>> "Vadim" == Vadim Tkachenko <vadim@stripped> writes:
Vadim> Thread-pool should be used very carefully.
Vadim> We tested it and InnoDB hangs in sysbench benchmarks when count of
Vadim> client connection > size of thread-pool.
Yes, this a problem when you have more locks than threads.
The innodb deadlock detector has to timeout the hanged items.
Vadim> The problem is transaction state. Some connections may do internals
Vadim> locks and after that could not enter to pool, because all slots are busy.
Vadim> I expect you will have the same problem with Maria when it can fully
Vadim> support transactions.
That is one of the main reasons I added --extra-port to MariaDB
This allows you to connect and check/kill things if you get a hang.
So things are not perfect now, but at least a little better.
In the future we have to also look at creating more pool-threads when
all pool-threads gets locked by a handler.