View the concurrent connections and connection status of Nginx Apache MySQL under Linux

1. View the number of concurrent requests for the Web server (Nginx Apache) and its TCP connection status:

Netstat-n | awk '/^tcp/{++s[$NF]} END {for (a in S) print A, s[a]} '

Or:
Netstat-n | awk '/^tcp/{++state[$NF]} END {for (key in) print key, "T", State[key]} '

The returned results are generally as follows:

Last_ack 5 (number of requests waiting to be processed)
SYN_RECV 30
Established 1597 (normal data transfer status, can be understood as close to the number of concurrent connections)
Fin_wait1 51
Fin_wait2 504
Time_wait 1057 (number of requests processed, waiting for timeout to end)

Additional parameter Description:

CLOSED: No connection is active or in progress
LISTEN: The server is waiting to enter the call
SYN_RECV: A connection request has arrived, waiting for confirmation
Syn_sent: Application has started, open a connection
Established: Normal data transfer status
FIN_WAIT1: Application says it's done
Fin_wait2: The other side has agreed to release
Itmed_wait: Waiting for all packets to die
CLOSING: Both sides try to close simultaneously
Time_wait: The other side has initialized a release
Last_ack: Waiting for all packets to die

2. View the number of nginx concurrent processes
Ps-ef | grep Nginx | Wc-l
The number returned is Nginx is not the number of processes, if Apache is executed
Ps-ef | grep httpd | Wc-l

You can also use the following command:
Watch-n 1-d "Pgrep nginx|wc-l"

3. View the number of Web server process connections:
NETSTAT-ANTP | grep 80 | grep established-c

4. View the number of MySQL process connections:
Ps-axef | grep mysqld-c

View the concurrent connections and connection status of Nginx Apache MySQL under Linux