The connection-start and
connection-done probes enclose a connection
from a client, regardless of whether the connection is through a
socket or network connection.
connection-start(connectionid, user, host) connection-done(status, connectionid)
connection-start: Triggered after a connection and successful login/authentication have been completed by a client. The arguments contain the connection information:connectionid: Anunsigned longcontaining the connection ID. This is the same as the process ID shown as theIdvalue in the output fromSHOW PROCESSLIST.user: The username used when authenticating. The value will be blank for the anonymous user.host: The host of the client connection. For a connection made using UNIX sockets, the value will be blank.
connection-done: Triggered just as the connection to the client has been closed. The arguments are:status: The status of the connection when it was closed. A logout operation will have a value of 0; any other termination of the connection has a nonzero value.connectionid: The connection ID of the connection that was closed.
The following D script will quantify and summarize the average duration of individual connections, and provide a count, dumping the information every 60 seconds:
#!/usr/sbin/dtrace -s
mysql*:::connection-start
{
self->start = timestamp;
}
mysql*:::connection-done
/self->start/
{
@ = quantize(((timestamp - self->start)/1000000));
self->start = 0;
}
tick-60s
{
printa(@);
}
When executed on a server with a large number of clients you might see output similar to this:
1 57413 :tick-60s
value ------------- Distribution ------------- count
-1 | 0
0 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 30011
1 | 59
2 | 5
4 | 20
8 | 29
16 | 18
32 | 27
64 | 30
128 | 11
256 | 10
512 | 1
1024 | 6
2048 | 8
4096 | 9
8192 | 8
16384 | 2
32768 | 1
65536 | 1
131072 | 0
262144 | 1
524288 | 0