Recently found out my MySQL server hits 90% high CPU utilization when simulating over concurrent 100-500 threads request
with the default settings plus following in my.cnf
max_connections = 500 max_allowed_packet = 16M
I notice the max_connection can hit up to 500, threads_created can also go high to 200-500 and i'm thinking this has actually cause abnormally high CPU
Hence instead of using default settings i adjusted
innodb_buffer_pool_size = 2G #32bit linux server innodb_log_file_size = 256M innodb_log_buffer_size = 8M innodb_thread_concurrency = 16 innodb_flush_method = O_DIRECT innodb_additional_mem_pool_size = 20M table_cache = 1028 thread_cache_size = 16 key_buffer_size=32M query_cache_size=32M join_buffer_size=1M
With the same load testing, the CPU dived down to 10% and below... However i notice the max_connection never hits 500 anymore. It is less than 50 now...
Is this caused by thread_cache_size i've adjusted? by default it is 0. Or is there something wrong somewhere ... I'm wondering in that case if the mysql server is correctly tested with the max connection. I want to test how if concurrent threads can hit the max_connections but somehow it never hit with the same amount i tested before. Since the change, it never hits above 50 now.