src/test/singlenode_isolation2/sql/resgroup/resgroup_cpuset_empty_default.sql

-- A regression test for cpuset.
--
-- When all the cpu cores are allocated the default cpuset group should
-- fallback to core 0.  However this fallback logic was only added on
-- CREATE / ALTER RESOURCE GROUP, but missing in startup logic, an empty cpu
-- core list "" is set to cgroup and cause a runtime error:
--
--     can't write data to file '/sys/fs/cgroup/cpuset/gpdb/1/cpuset.cpus':
--       No space left on device (resgroup-ops-linux.c:916)
--
-- To trigger the issue we create a resource group, allocate all the cpu cores
-- to it, and restart the cluster.

-- start_ignore
DROP RESOURCE GROUP rg1_cpuset_test;
-- end_ignore

-- Create a resource group with all the cpu cores.
-- The isolation2 test framework does not support \set so we have to plan with
-- some tricks.
! psql -d isolation2resgrouptest -Ac "CREATE RESOURCE GROUP rg1_cpuset_test WITH (memory_limit=10, cpuset='0-$(($(nproc)-1))')";

-- Alter a resource group from / to all the cpu cores should also work.
ALTER RESOURCE GROUP rg1_cpuset_test SET cpuset '0';
! psql -d isolation2resgrouptest -Ac "ALTER RESOURCE GROUP rg1_cpuset_test SET cpuset '0-$(($(nproc)-1))'";

-- start_ignore
! gpstop -rai;
-- end_ignore

-- Cleanup in a new connection as the default one is disconnected by gpstop
10: DROP RESOURCE GROUP rg1_cpuset_test;