Connection Probes

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: An unsigned long containing the connection ID. This is the same as the process ID shown as the Id value in the output from SHOW 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:

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