Describe the bug

SRANDMEMBER should return random elements from the specified set, instead, it only returns the lowest scoring element(s).

The SPOP command has the same problem, each time it removes only the lowest scoring element(s) from the set.

To Reproduce

SRANDMEMBER

The steps to reproduce the behavior of the SRANDMEMBER command:

1. Inserting elements into a set: redis-cli SADD myset one two three four five six seven eight nine ten
2. Сalling SRANDMEMBER multiple times: seq 20 | xargs -I {} redis-cli SRANDMEMBER myset

The result is always "eight".

SPOP

The steps to reproduce the SPOP behavior are more tricky. After each deletion of an element, we must return it back to the set in order to keep the same set of elements:

1. Insert elements into a set: redis-cli SADD myset one two three four five six seven eight nine ten

2. Remove the element and return it back multiple times: for i in {1..20}; do redis-cli SPOP myset | tee -a removed_members.txt | xargs -I {} redis-cli SADD myset {}; done

   • Notice: between running SPOP and SADD, we write the SPOP result to the file removed_members.txt. As a result, in removed_members.txt we can see which elements were deleted during the SPOP commands.

In removed_members.txt we can see that "eight" was deleted each time.

Expected behavior

It is expected that both commands return/remove a pseudo random element for each invocation.

SRANDMEMBER

$ seq 20 | xargs -I {} redis-cli SRANDMEMBER x 1
1) two
1) six
1) two
1) two
1) nine
1) three
1) five
1) two
1) ten
1) ten
1) nine
1) four
1) eight
1) two
1) five
1) three
1) five
1) four
1) nine
1) ten

SPOP

$ cat removed_members.txt
ten
nine
four
five
eight
eight
one
nine
two
nine
three
five
four
nine
eight
five
four
two
six
two

Environment (please complete the following information):

• OS: ubuntu 20.04
• Containerized: Docker
• Dragonfly Version: v1.17.0

Reproducible Code Snippet

SRANDMEMBER

redis-cli SADD myset one two three four five six seven eight nine ten
seq 20 | xargs -I {} redis-cli SRANDMEMBER myset

SPOP

redis-cli SADD myset one two three four five six seven eight nine ten
for i in {1..30}; do redis-cli SPOP myset | tee -a removed_members.txt | xargs -I {} redis-cli SADD myset {}; done
cat removed_members.txt

Additional context

The problem is very similar to #2850.