php连接 mysql，稍微有点并发量的时候会出现数据库链接失败的情况

悬赏园豆：10 [待解决问题]

硬件环境：CPU ==》X5672*2 内存：32G 硬盘：240G SSD

系统：LINUX CentOS 6.8

软件环境：

PHP：5.6 ， nginx，1.14

MYSQL：5.6

分别贴出php 配置和 mysql 配置

[global]
pid = /www/server/php/56/var/run/php-fpm.pid
error_log = /www/server/php/56/var/log/php-fpm.log
log_level = notice

[www]
listen = /tmp/php-cgi-56.sock
listen.backlog = -1
listen.allowed_clients = 127.0.0.1
listen.owner = www
listen.group = www
listen.mode = 0666
user = www
group = www
pm = dynamic
pm.status_path = /phpfpm_56_status
pm.max_children = 300
pm.start_servers = 30
pm.min_spare_servers = 30
pm.max_spare_servers = 300
request_terminate_timeout = 100
request_slowlog_timeout = 30
slowlog = var/log/slow.log

PHP-cgi配置

[client]
#password   = your_password
port        = 3306
socket      = /tmp/mysql.sock

[mysqld]
binlog_cache_size = 192K
thread_stack = 384K
join_buffer_size = 4096K
query_cache_type = 0
max_heap_table_size = 1024M
port        = 3306
socket      = /tmp/mysql.sock
datadir = /www/server/data
skip-external-locking
performance_schema_max_table_instances=400
table_definition_cache=400
key_buffer_size = 512M
max_allowed_packet = 100G
table_open_cache = 1024
sort_buffer_size = 2048K
net_buffer_length = 8K
read_buffer_size = 2048K
read_rnd_buffer_size = 1024K
myisam_sort_buffer_size = 64M
thread_cache_size = 192
query_cache_size = 0M
tmp_table_size = 1024M

explicit_defaults_for_timestamp = true
#skip-networking
skip-name-resolve
skip-grant-tables
max_connections = 16384
max_connect_errors = 100
open_files_limit = 65535
sql-mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES

#log-bin=mysql-bin
#binlog_format=mixed
server-id   = 1
expire_logs_days = 10
slow_query_log=1
slow-query-log-file=/www/server/data/mysql-slow.log
long_query_time=3
back_log = 900
#log_queries_not_using_indexes=on

#loose-innodb-trx=0
#loose-innodb-locks=0
#loose-innodb-lock-waits=0
#loose-innodb-cmp=0
#loose-innodb-cmp-per-index=0
#loose-innodb-cmp-per-index-reset=0
#loose-innodb-cmp-reset=0
#loose-innodb-cmpmem=0
#loose-innodb-cmpmem-reset=0
#loose-innodb-buffer-page=0
#loose-innodb-buffer-page-lru=0
#loose-innodb-buffer-pool-stats=0
#loose-innodb-metrics=0
#loose-innodb-ft-default-stopword=0
#loose-innodb-ft-inserted=0
#loose-innodb-ft-deleted=0
#loose-innodb-ft-being-deleted=0
#loose-innodb-ft-config=0
#loose-innodb-ft-index-cache=0
#loose-innodb-ft-index-table=0
#loose-innodb-sys-tables=0
#loose-innodb-sys-tablestats=0
#loose-innodb-sys-indexes=0
#loose-innodb-sys-columns=0
#loose-innodb-sys-fields=0
#loose-innodb-sys-foreign=0
#loose-innodb-sys-foreign-cols=0

default_storage_engine = InnoDB
innodb_data_home_dir = /www/server/data
innodb_data_file_path = ibdata1:10M:autoextend
innodb_log_group_home_dir = /www/server/data
innodb_buffer_pool_size = 20480M
innodb_log_file_size = 512M
innodb_log_buffer_size = 128M
innodb_flush_log_at_trx_commit = 1
innodb_lock_wait_timeout = 100
innodb_max_dirty_pages_pct = 90
innodb_read_io_threads = 16
innodb_write_io_threads = 16
innodb_io_capacity=3000
[mysqldump]
quick
max_allowed_packet = 16M

[mysql]
no-auto-rehash

[myisamchk]
key_buffer_size = 256M
sort_buffer_size = 4M
read_buffer = 2M
write_buffer = 2M

[mysqlhotcopy]
interactive-timeout

数据库表：类型：MyISAM

数据库引擎用的是：InnoDB

在高并发的时候：数据库查看最大使用连接数是：5400

没有拥堵的执行语句，基本上都是用 insert和update 的比较多一些，查询量非常小，

linux使用情况如图

linux 链接情况：

当出现大量操作语句的时候，会导致数据库连接失败，不仅仅服务器，本地的navicat 也链接不上，考虑到是否是linux的连接数太大造成的，本人另外测试了在当前机器上发布一版本，利用jmeter 做链接请求，200个线程，每个线程请求200次，本地网络不是特别好，跑了大概一分钟左右，刚开始没有出现链接不上的情况，而且并发处理速度特别快，跑了一万次请求的时候，开始，就变卡，变慢，然后出现数据库连接不上的情况。

请问各位mysql 或PHP 大神指教下，我改如何修正

cpu 和内存均消耗不超过30%，基本上在20%-30%之间，(次数据是用linux工具查看的，不一定非常准确)