This PR contains two features:

1. After load modules from queue generated by config "loadmodule" option, we can empty the queue to free unnecessary memory.

2. Rewrite config "loadmodule" option is necessary I think, thus we can load all modules after reboot.

What do you think about it @antirez ?

Thank you, PR checked, everything looks sane but I've to think a bit about the fact of rewriting the config. Probably a good idea but just taking a few days to consider this. Going to merge for RC2 for sure. Thanks.

IIUC, the aim here is that if someone uses the MODULE LOAD or MODULE UNLOAD commands, and then CONFIG REWRITE, the new module list will be reflected in the generated config file, right?
i suppose that's logical (same thing happens with ACL), since it's a behaviour change, we need to introduce it in 7.0.
@soloestoy can you please rebase / refresh this, and update the top comment?
@yossigo @madolson do you see any problem with that?

@oranagra No, I think that makes sense.

Sounds good to me as well.

I just rebased this PR.

BTW, do you think we should show the path and args in MODULE LIST command's reply? I didn't push the original commit, if you think it's necessary I can push it.

i think it can be nice to add the full path and args to the MODULE LIST response with more fields.
it can be part of this PR, or a different ones (both are major decision anyway).

@soloestoy shall we merge this with a rebase-merge or a squash merge?
i see 3 individual commits and 3 distinct topics, so if you can confirm they're indeed completely independent, we can use rebase-merge.

also, i'd like to add a test for the CONFIG REWRITE part.
do you wanna do that as part of this PR, or shall we ask for some volunteer after it is merged?

Hi @soloestoy!

I maintain a secondary.confconfiguration file for loadmodule and other configurations and include them it in the primary.conf file which I use to start the redis-server (Redis version=7.0.10).

The primary.conf and secondary.conf look like this,

primary.conf

...
include /home/vikram/redis7/secondary.conf
...

secondary.conf

...
loadmodule /home/vikram/redis7/aclcheck.so
...

1. I did not encounter any errors when I first started the redis-server withprimary.conf.

redis7>./redis-server ./primary.conf

10755:C 04 Apr 2023 15:16:09.690 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
10755:C 04 Apr 2023 15:16:09.690 # Redis version=7.0.10, bits=64, commit=00000000, modified=0, pid=10755, just started
10755:C 04 Apr 2023 15:16:09.690 # Configuration loaded
10755:M 04 Apr 2023 15:16:09.692 * monotonic clock: POSIX clock_gettime
10755:M 04 Apr 2023 15:16:09.693 # Server initialized
10755:M 04 Apr 2023 15:16:09.694 * Module 'aclcheck' loaded from /home/vikram/redis7/aclcheck.so
10755:M 04 Apr 2023 15:16:09.695 * Ready to accept connections

2. Then after executing CONFIG REWRITE , the primary.conf file was appended with 'loadmodule /home/vikram/redis7/aclcheck.so' as said in Modules: rewrite loadmodule and extend LIST reply #4848.

redis7>./redis-cli CONFIG REWRITE

primary.conf file after CONFIG REWRITE

include /home/vikram/redis7/secondary.conf

# Generated by CONFIG REWRITE
...
loadmodule /home/vikram/redis7/aclcheck.so
...

3. Now on redis-server restart, I am facing the below error because during startup there are two loadmodule directives for the same module, one from secondary.conf and one from primary.conf.

redis7> ./redis-server ./primary.conf

11671:C 04 Apr 2023 15:17:37.469 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
11671:C 04 Apr 2023 15:17:37.469 # Redis version=7.0.10, bits=64, commit=00000000, modified=0, pid=11671, just started
11671:C 04 Apr 2023 15:17:37.469 # Configuration loaded
11671:M 04 Apr 2023 15:17:37.470 * monotonic clock: POSIX clock_gettime
11671:M 04 Apr 2023 15:17:37.472 # Server initialized
11671:M 04 Apr 2023 15:17:37.473 * Module 'aclcheck' loaded from /home/vikram/redis7/aclcheck.so
11671:M 04 Apr 2023 15:17:37.473 # Module /home/vikram/redis7/aclcheck.so initialization failed. Module not loaded
11671:M 04 Apr 2023 15:17:37.473 # Can't load module from /home/vikram/redis7/aclcheck.so: server aborting