Bug #80073 memcached plugin does not load with libevent 2.0
Submitted: 20 Jan 2016 13:04 Modified: 8 Feb 2016 17:03
Reporter: Erlend Dahl Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Compiling Severity:S3 (Non-critical)
Version:5.7 OS:Any
Assigned to: CPU Architecture:Any

[20 Jan 2016 13:04] Erlend Dahl 
Description:
Compile the server with the InnoDB Memcached plugin and bundled libevent (version 2.0.21 on Ubuntu 15.10):

cmake ../mysql -DWITH_INNODB_MEMCACHED=1 -DWITH_LIBEVENT=system -DDOWNLOAD_BOOST=1 -DWITH_BOOST=/home/edahl/boost -DWITH_DEBUG=1 -DWITH_EMBEDDED_SERVER=0 -DWITH_SSL=system

Run the MTR memcached test suite:

./mtr --mem --suite=memcached

This gives:

mysqltest: At line 48: query 'INSTALL PLUGIN daemon_memcached SONAME 'libmemcached.so'' failed: 1126: Can't open shared library '/home/edahl/bzr/build-trunk-debug/plugin/innodb_memcached/daemon_memcached/libmemcached.so' (errno: 2 /home/edahl/bzr/build-trunk-debug/plugin/innodb_memcached/daemon_memcached/libmemcached.so: undefined symbol: event_base_set)

How to repeat:
As above. 

Maybe related to the existence of two libevent libraries on Ubuntu: libevent.so and libevent_core.so. The missing symbol is in the second library.
[22 Jan 2016 13:25] Erlend Dahl 
Posted by developer:
 
Correction: the above says "compiled with bundled libevent" - it should of course be "system libevent".
[8 Feb 2016 17:03] Paul DuBois 
Noted in 5.8.0 changelog.

Compiling the InnoDB memcached plugin did not work on some platforms
if MySQL was configured using -DWITH_LIBEVENT=system.
[18 Dec 2018 16:40] Paul DuBois 
Posted by developer:
 
Fixed in 5.6.44.
[18 Dec 2018 16:44] Paul DuBois 
Posted by developer:
 
Ignore previous comment; meant to post it to a different bug.