Configuring the Windows registry: TCP/IP buffers and connections

If your parallel engine is installed on a server that runs Microsoft® Windows®, check the TCP/IP buffers and connections, and change them if necessary.

About this task

You can check to see if the following two keys are defined in your registry:

MaxUserPort
TcpNumConnections

These keys are not added to the registry by default. The TcpNumConnections has a major impact on the number of concurrent osh processes allowed.

Procedure

To check, and if necessary edit or add the registry keys, do the following steps:

Select Start > Run > regedit.exe to start the Registry Editor.
Browse to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters keys.
If the MaxUserPort and TcpNumConnections are not there, then add them by doing the following steps:
1. Select Edit > New.
2. Add the MaxUserPort key by setting the following fields:
  - Value Name: MaxUserPort
  - Value Type: DWORD
  - Value data: 65534
  - Valid Range: 5000-65534 (decimal)
  - Default: 0x1388 (5000 decimal)
  - Description: This parameter controls the maximum port number that is used when a program requests any available user port from the server. Typically, ephemeral (short-lived) ports are allocated between the values of 1024 and 5000 inclusive.
3. Select Edit > New
4. Add the TcpNumConnections key by setting the following fields:
  - value Name: TcpNumConnections
  - Value Type: DWORD
  - Value data: 65534
  - Valid Range: 0 - 0xfffffe (65534 decimal)
  - Default: 0xfffffe
  - Description: This parameter limits the maximum number of connections that TCP can have open at the same time.
Close the Registry Editor.
Restart the computer.