LOADING Redis is loading the dataset in memory

When the system is not prepared to accept connection requests, this Redis error is displayed. When Redis has finished loading data into memory, it usually disappears, but occasionally it lingers.

We assist our clients in resolving Redis-related errors like this as a part of our Server Management Services.

Today, we’ll examine the causes of persistent memory errors and possible solutions.

What results in “ERROR: LOADING Redis is loading the dataset in memory”?

Redis keeps all of the data in memory and responds to all requests with data from that memory. This frequently speeds up the loading of applications.

Replica Redis instances can be exact duplicates of master instances thanks to the Redis replication system. The replica will attempt to be an exact copy of the master regardless of what happens to the master whenever the link breaks.

If connections are requested before the system has finished loading the dataset into memory and has made Redis ready for connections, the “LOADING Redis is loading the dataset in memory” error will appear. Typically, this occurs in two different circumstances:

1. At a master startup.
2. When a slave reconnects and resynchronizes completely with a master.

Now let’s check the potential fixes for this issue.

How to resolve the “LOADING Redis is loading the dataset in memory” error?

Most of the time, recent site changes made in relation to Redis can be the reason for the error message appearing frequently. This could significantly increase the amount of data in Redis, which is easily saturated. Therefore, Redis replicas may frequently become disconnected. Finally, it may attempt to reconnect and display the message “LOADING Redis is loading the dataset in memory.”

Flushing the Redis cache would be the quick fix in this situation. Let’s talk about how to fix the Redis cache:

Flush Redis Cache

Either the FLUSHDB or FLUSHALL command may be used to Flush the Redis Cache. The FLUSHALL command removes all of the keys from all of the existing databases, not just the one that was selected, while the FLUSHDB command removes all of the keys from the DBs that were selected.

The syntax for commands is as follows:

redis-cli FLUSHDB
redis-cli -n DB_NUMBER FLUSHDB
redis-cli -n DB_NUMBER FLUSHDB ASYNC
redis-cli FLUSHALL
redis-cli FLUSHALL ASYNC

For instance, the following syntax should be used to remove all of the keys from database #4 from the Redis cache:

$ redis-cli -n 4 FLUSHDB

This will aid in resolving the problem. We need to undo the previous changes to stop them from happening frequently. It is always preferable to keep Redis’s information as simple as possible.

Conclusion

In brief, when the Redis master starts up or when the slave reconnects and completes a complete resynchronization with the master, the error “LOADING Redis is loading the dataset in memory” occurs. The error message is triggered when these connection requests arrive before the dataset has fully loaded into memory. We talked about how our Tech Support fixed this issue.

Are you looking for an answer to another query? Contact our technical support team.