redis replication scheduled to be closed ASAP for overcoming of output buffer limits.

redis-client-ouput-buffer-limit

If you redis initial replication fails with error like 
"5101:M 20 Feb 18:14:29.130 # Client id=4500196 addr=71.459.815.760:43872 fd=533 name= age=127 idle=127 flags=S db=0 sub=0 psub=0 multi=-1 qbuf=0 qbuf-free=0 obl=13997 oll=1227 omem=192281275 events=rw cmd=psync scheduled to be closed ASAP for overcoming of output buffer limits.

means that slave buffer is not enough and you should increase it (at master!) with command like
redis-cli config set client-output-buffer-limit "slave 836870912 836870912 0"

more info: https://redis.io/topics/clients

These errors can also happen for the pubsub buffer overruns, not only the slave buffers.

The errors we see in the log that are related to pubsub buffer overruns are something like:

<timestamp> # Client id=494028 addr=127.0.0.1:43534 fd=36 name= age=75 idle=0 flags=N db=0 sub=148630 
    psub=0 multi=-1 qbuf=0 qbuf-free=32768 obl=0 oll=742 omem=12154393 events=rw 
    cmd=subscribe scheduled to be closed ASAP for overcoming of output buffer limits.

By increasing the client-output-buffer-limit pubsub <hard> <soft> <seconds> this may be resolved as well.

you can set this in a running production server by

redis-cli config set client-output-buffer-limit "pubsub <hard> <soft> <seconds>"

# eg to set it to 64 MB hard, 32 MB soft for 120s:
redis-cli config set client-output-buffer-limit "pubsub 64mb 32mb 120"

or put it in the redis.conf and find and replace the client-output-buffer-limit pubsub line

Thanks for this post for guiding our thoughts and eventually saving our lives as well.

also my life, thank you!

@jberends

Thanks for the help!
These manipulations require AUTH password to submit changes.

redis-cli config -a "$REDIS_PASSWORD" set client-output-buffer-limit "pubsub 64mb 32mb 120"

It must return OK if a request is successful.

I can't use "mb" in redis-cli command for server version 4.0.9.
I must specify pure numbers in the command:

redis-cli config set client-output-buffer-limit "pubsub 268435456 67108864 120"

TO THE MOON

Thank you. Helpful hint.
I knew there is some buffer but official documentation was missing that info.

Thanks this is helpful!

Me too :) Thanks a lot

too bad I got here after the crash loop. Still, very helpful, thanks!

you saved my life as well 🙏