As part of the PostgreSQL series, in today’s tutorial, we are going to see on how to deal with one of the most often seen postgresql errors:
org.postgresql.util.PSQLException: FATAL: sorry, too many clients already.
The error it’s pretty much self explanatory, and this is only the symptom. There is a default db connection limit of
100, and it’s seems like it’s full.
- Increase the
max_connectionsparameter. This is the most easiest one, and probably will work as a temporary solution until you figure it out the rest of the following solutions.
- There could be a leakage, the client connections aren’t properly closed on the backend side, so find out why is that.
- Use a connection pooler.
Let’s focus on solution #1, so you can buy some time preparing for the other two solutions.
Step 1. First things first, check the
max_connections parameter value.
Step 2. List the number of connections currently used.
SELECT count(*) FROM pg_stat_activity;
Step 3. You can also take a look more into details regarding the current connections.
SELECT * FROM pg_stat_activity;
Step 4. Open the postgres config file
/var/lib/postgresql/data/postgresql.conf and update the
max_connections = 100
Note: Increasing the
max_connections parameter only, is a bad idea, you need to update
shared_buffers as well. It determines how much memory will be used by PostgreSQL for caching data. By default, the
shared_buffers value should be 25% of the total memory in the server. With that being said…
Step 5. Let’s say we got a server with 8GB memory, and in the same
postgresql.conf file, update the
shared_buffers parameter value to 2GB.
shared_buffers = 2GB
Step 6. Restart the PostgreSQL service.
systemctl restart postgresql
Not a huge fan of fixing symptoms, and increasing
max_connections it’s not always a good solution, but it’ll buy you some time, especially if you dealing with this one on Friday.
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