(mysql.info) can-not-connect-to-server-on-windows

(mysql.info) can-not-connect-to-server
 
 A.2.2.1 `Connection to MySQL Server Failing on Windows'
 .......................................................
 
 When you're running a MySQL server on Windows with many TCP/IP
 connections to it, and you're experiencing that quite often your
 clients get a `Can't connect to MySQL server' error, the reason might
 be that Windows doesn't allow for enough ephemeral (short-lived) ports
 to serve those connections.
 
 By default, Windows allows 5000 ephemeral (short-lived) TCP ports to
 the user. After any port is closed it will remain in a `TIME_WAIT'
 status for 120 seconds. This status allows the connection to be reused
 at a much lower cost than reinitializing a brand new connection.
 However, the port will not be available again until this time expires.
 
 With a small stack of available TCP ports (5000) and a high number of
 TCP ports being open and closed over a short period of time along with
 the `TIME_WAIT' status you have a good chance for running out of ports.
 There are two ways to address this problem:
 
    * Reduce the number of TCP ports consumed quickly by investigating
      connection pooling or persistent connections where possible
 
    * Tune some settings in the Windows registry (see below)
 
 * IMPORTANT: The following procedure involves modifying the Windows
 registry. Before you modify the registry, make sure to back it up and
 make sure that you understand how to restore the registry if a problem
 occurs.  For information about how to back up, restore, and edit the
 registry, view the following article in the Microsoft Knowledge Base:
 `http://support.microsoft.com/kb/256986/EN-US/'.  *
 
   1. Start Registry Editor (`Regedt32.exe').
 
   2. Locate the following key in the registry:
 
           HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
 
   3. On the `Edit' menu, click `Add Value', and then add the following
      registry value:
 
           Value Name: MaxUserPort
           Data Type: REG_DWORD
           Value: 65534
 
      This sets the number of ephemeral ports available to any user. The
      valid range is between 5000 and 65534 (decimal).  The default
      value is 0x1388 (5000 decimal).
 
   4. On the `Edit' menu, click `Add Value', and then add the following
      registry value:
 
           Value Name: TcpTimedWaitDelay
           Data Type: REG_DWORD
           Value: 30
 
      This sets the number of seconds to hold a TCP port connection in
      `TIME_WAIT' state before closing. The valid range is between 0
      (zero) and 300 (decimal). The default value is 0x78 (120 decimal).
 
   5. Quit Registry Editor.
 
   6. Reboot the machine.
 
 Note: Undoing the above should be as simple as deleting the registry
 entries you've created.
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