Below the rds parameter group config, please help me to resolve this issue. I am using 4 web server having 2 CPU and 8 GB ram and rds having 4 cpu and 16 GB ram.

Once the connection reached 50 site will stop responding.

join_buffer_size                        150.00 MB
read_buffer_size                        150.00 MB
read_rnd_buffer_size                    300.00 MB
sort_buffer_size                        150.00 MB
Total for max_connections=600           750.00 MB

2 Answers 2


In your .cfg/ini [mysqld] section consider using

max_connections=100  # since you are stymied at 50 connections

the last 4 are allocated at connection and your values are over the top, my recommendations are close to defaults suggested in refman. thread_cache_size=50 would prevent most threads created thrashing.


There may be many causes here are some suggestions:

1) Check slow query log in mysql:


2) Change mysql driver in your application

Even if you downgrade it, you can have better results. Change a major version if possible.

3) Look for locks

mysqladmin debug

It will dump a lot of information, including locks, but you can get lock information by queries too:


Hope it helps

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