A.2.6. Too many connections
If you get a Too many connections error when
you try to connect to the mysqld server, this
means that all available connections are in use by other
clients.
The number of connections allowed is controlled by the
max_connections system variable. Its default
value is 100. If you need to support more connections, you
should restart mysqld with a larger value for
this variable.
mysqld actually allows
max_connections+1 clients to connect. The
extra connection is reserved for use by accounts that have the
SUPER privilege. By granting the
SUPER privilege to administrators and not to
normal users (who should not need it), an administrator can
connect to the server and use SHOW
PROCESSLIST to diagnose problems even if the maximum
number of unprivileged clients are connected. See
Section 13.5.4.22, “SHOW PROCESSLIST Syntax”.
The maximum number of connections MySQL can support depends on
the quality of the thread library on a given platform. Linux or
Solaris should be able to support 500-1000 simultaneous
connections, depending on how much RAM you have and what your
clients are doing. Static Linux binaries provided by MySQL AB
can support up to 4000 connections.
