Mystery solved. I had upgraded two different servers from debian mysql 5.6 and oracle mysql 5.7 to mariadb-10.3. The packages were drop in replacements, but when I removed libjemalloc1, mariadb wouldn't start because my former DBA had put this in my.cnf:
[mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 malloc-lib = /usr/lib/x86_64-linux-gnu/libjemalloc.so.1 Commenting that line out, or putting in libjemalloc2 and changing it to .so.2 both work fine. Thanks for looking at it and sorry for the trouble. This can be closed.
