Mysql optimization advice

Question

I don't understand very well about servers and mysql, I just have an android application running, and when it reaches 1800 simultaneous users the server slows down. I don't know if it's normal or if I can optimize something

my android app has a laravel backend and the app code is java

Server Config

16 vCPU Intel Xeon 2.1 GHz 30 GB RAM DDR4 1 TB SSD

my my.cnf

[mysql]
port                            = 3306
socket                          = /var/lib/mysql/mysql.sock

[mysqld]
performance_schema = ON
# === Required Settings ===
basedir                         = /usr
bind_address                    = 127.0.0.1 # Change to 0.0.0.0 to allow remote connections
datadir                         = /var/lib/mysql
#default_authentication_plugin  = mysql_native_password # Enable in MySQL 8+ or MariaDB 10.6+ for backwards compatibility with common CMSs
max_allowed_packet              = 256M
max_connect_errors              = 1000000
pid_file                        = /var/lib/mysql/mysql.pid
port                            = 3306
skip_external_locking
socket                          = /var/lib/mysql/mysql.sock
tmpdir                          = /tmp
user                            = mysql

# === SQL Compatibility Mode ===
# Enable for b/c with databases created in older MySQL/MariaDB versions
# (e.g. when using null dates)
#sql_mode                       = ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION,ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES
# Crappy SQL queries/schema? Go bold!
#sql_mode                       = ""

# === InnoDB Settings ===
default_storage_engine          = InnoDB
innodb_buffer_pool_instances    = 27     # Use 1 instance per 1GB of InnoDB pool size - max is 64
innodb_buffer_pool_size         = 27G    # Use up to 70-80% of RAM
innodb_file_per_table           = 1
innodb_flush_log_at_trx_commit  = 0
innodb_flush_method             = O_DIRECT
innodb_log_buffer_size          = 16M
innodb_log_file_size            = 3G
innodb_sort_buffer_size         = 64M    # UPD - Defines how much data is read into memory for sorting operations before writing to disk (default is 1M / max is 64M)
innodb_stats_on_metadata        = 0
innodb_lru_scan_depth           = 100
# thread_pool_size                = 6

# innodb_use_fdatasync           = 1     # Only (!) for MySQL v8.0.26+

innodb_temp_data_file_path     = ibtmp1:64M:autoextend:max:20G # Control the maximum size for the ibtmp1 file
innodb_thread_concurrency      = 15     # Optional: Set to the number of CPUs on your system (minus 1 or 2) to better
                                        # contain CPU usage. E.g. if your system has 8 CPUs, try 6 or 7 and check
                                        # the overall load produced by MySQL/MariaDB.
innodb_read_io_threads          = 64
innodb_write_io_threads         = 64
innodb_io_capacity             = 2000  # Depends on the storage tech - use 2000 for SSD, more for NVMe
innodb_io_capacity_max         = 4000  # Usually double the value of innodb_io_capacity

# === MyISAM Settings ===
# The following 3 options are ONLY supported by MariaDB & up to MySQL 5.7
# Do NOT un-comment on MySQL 8.x+
query_cache_limit              = 64M    # UPD
query_cache_size               = 64M   # UPD
query_cache_type               = DEMAND     # Enabled by default

key_buffer_size                 = 1G   # UPD

low_priority_updates            = 1
concurrent_insert               = 2

# === Connection Settings ===
max_connections                 = 30   # UPD - Important: high no. of connections = high RAM consumption

back_log                        = 512
thread_cache_size               = 100
thread_stack                    = 192K

interactive_timeout             = 180
wait_timeout                    = 180

# For MySQL 5.7+ only (disabled by default)
max_execution_time             = 9000 # Set a timeout limit for SELECT statements (value in milliseconds).
                                        # This option may be useful to address aggressive crawling on large sites,
                                        # but it can also cause issues (e.g. with backups). So use with extreme caution and test!
                                        # More info at: https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_max_execution_time

# For MariaDB 10.1.1+ only (disabled by default)
#max_statement_time             = 90    # The equivalent of "max_execution_time" in MySQL 5.7+ (set above)
                                        # The variable is of type double, thus you can use subsecond timeout.
                                        # For example you can use value 0.01 for 10 milliseconds timeout.
                                        # More info at: https://mariadb.com/kb/en/aborting-statements/

# === Buffer Settings ===
# Handy tip for managing your database's RAM usage:
# The following values should be treated carefully as they are added together and then multiplied by your "max_connections" value.
# Other options will also add up to RAM consumption (e.g. tmp_table_size). So don't go switching your "join_buffer_size" to 1G, it's harmful & inefficient.
# Use one of the database diagnostics tools mentioned at the top of this file to count your database's potential total RAM usage, so you know if you are within
# reasonable limits. Remember that other services will require enough RAM to operate properly (like Apache or PHP-FPM), so set your limits wisely.
join_buffer_size                = 40M    # UPD
read_buffer_size                = 30M    # UPD
read_rnd_buffer_size            = 40M    # UPD
sort_buffer_size                = 40M    # UPD

# === Table Settings ===
# In systemd managed systems like Ubuntu 16.04+ or CentOS 7+, you need to perform an extra action for table_open_cache & open_files_limit
# to be overriden (also see comment next to open_files_limit).
# E.g. for MySQL 5.7, please check: https://dev.mysql.com/doc/refman/5.7/en/using-systemd.html
# and for MariaDB check: https://mariadb.com/kb/en/library/systemd/
table_definition_cache          = 600000 # UPD
table_open_cache                = 600000 # UPD
open_files_limit                = 800000 # UPD - This can be 2x to 3x the table_open_cache value or match the system's
                                        # open files limit usually set in /etc/sysctl.conf and /etc/security/limits.conf
                                        # In systemd managed systems this limit must also be set in:
                                        # - /etc/systemd/system/mysql.service.d/override.conf (for MySQL 5.7+ in Ubuntu) or
                                        # - /etc/systemd/system/mysqld.service.d/override.conf (for MySQL 5.7+ in CentOS) or
                                        # - /etc/systemd/system/mariadb.service.d/override.conf (for MariaDB)
                                        # otherwise changing open_files_limit will have no effect.
                                        #
                                        # To edit the right file execute:
                                        # $ systemctl edit mysql (or mysqld or mariadb)
                                        # and set "LimitNOFILE=" to something like 100000 or more (depending on your system limits for MySQL)
                                        # or use "LimitNOFILE=infinity" for MariaDB only.
                                        # Finally merge the changes with:
                                        # $ systemctl daemon-reload; systemctl restart mysql (or mysqld or mariadb)

max_heap_table_size             = 1G  # Increase to 256M or 512M if you have lots of temporary tables because of missing indices in JOINs
tmp_table_size                  = 1G  # Use same value as max_heap_table_size

# === Search Settings ===
ft_min_word_len                 = 3     # Minimum length of words to be indexed for search results

# === Binary Logging ===
disable_log_bin                 = 1     # Binary logging disabled by default
#log_bin                                # To enable binary logging, uncomment this line & only one of the following 2 lines
                                        # that corresponds to your actual MySQL/MariaDB version.
                                        # Remember to comment out the line with "disable_log_bin".
#expire_logs_days               = 1     # Keep logs for 1 day - For MySQL 5.x & MariaDB before 10.6 only
# binlog_expire_logs_seconds     = 86400 # Keep logs for 1 day (in seconds) - For MySQL 8+ & MariaDB 10.6+ only

# === Error & Slow Query Logging ===
log_error                       = /var/lib/mysql/mysql_error.log
log_queries_not_using_indexes   = 0     # Disabled on production
long_query_time                 = 5
slow_query_log                  = 1     # Disabled on production
slow_query_log_file             = /var/lib/mysql/mysql_slow.log

[mysqldump]
# Variable reference
# For MySQL 5.7+:  https://dev.mysql.com/doc/refman/5.7/en/mysqldump.html
# For MariaDB:     https://mariadb.com/kb/en/library/mysqldump/
quick
quote_names
max_allowed_packet=1024M

Answer 1

Firstly, I'd suggest that it's "unusual" to have android devices, "Out There" on the Wibbly-Wobbly Web, connecting directly to any database. it's far more usual (i.e. better practice) to have the client application talk to a web server which in turn talks to the database. There are many reasons for this, mostly revolving around the the [in]security of anything running "Out There" but also including scaling - web servers are built with "scaling out" (adding more capacity to handle more traffic) in mind. Databases are not.

Secondly, generally-speaking, databases servers do not slow down.
The queries that are run inside them do.

Start by looking to tune your Queries.

Then look to bolstering your architecture, adding a web server in the middle.
One thing that this will gain you is Connection Pooling - the web server can handle your 1800 incoming connections with only a few handfuls of database connections (and using database credentials that never leave your [safe] server environment).

Look to tune your database or server as a last resort, in the most extreme of cases.

• A Database Engineer spends several days poring over server and database configuration settings.
  They might get 2-3 Percentage Points improvement.
• A Developer spends several days designing proper database structures, indexing, etc.
  They might get 2-3 Orders of Magnitude improvement.