possible deadlock with ALTER + threadpool + events

Description

Am running the following on a slave:

  • Largish (24h, 600M rows, 200G) ALTER TABLE

  • Events with INFORMATION_SCHEMA queries

  • Threadpool pool-of-threads active

  • Replication 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.

Other notes:

  • 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.

Environment

Ubuntu 12.04 LTS Linux db1062 3.2.0-60-generic #91-Ubuntu SMP
Server version: 10.0.13-MariaDB-log Source distribution

Status

Assignee

Jan Lindström

Reporter

Sean Pringle

Labels

None

Fix versions

Affects versions

Priority

Major
Configure