Am running the following on a slave:
Largish (24h, 600M rows, 200G) ALTER TABLE
Events with INFORMATION_SCHEMA queries
Threadpool pool-of-threads active
No other significant traffic
After several hours, MariaDB locks up with 0% CPU and disk activity, and no response on existing or new connections on port, extra_port, or socket.
Attached are gdb backtraces for two occurrences, examples of the ALTER and the INFORMATION_SCHEMA activity, and other info. Would appreciate any insight from devs to identify the deadlock, and to narrow down the variables for a test case that isn't 200G.
Am presently trialing the ALTER outside the threadpool using the extra_port, with all other settings unchanged.
It doesn't seem to be a thread pool overload, as there aren't enough threads in the backtrace.
The INFORMATION_SCHEMA event traffic uses GET_LOCK to serialize some activity and prevent pile-up.
Ubuntu 12.04 LTS Linux db1062 3.2.0-60-generic #91-Ubuntu SMP
Server version: 10.0.13-MariaDB-log Source distribution