Jobs fail with There are no child processes to wait for


Check to make sure that the JAMS Scheduler server can reach the IMAP server on the specified port.

Unsecured transmission uses port 143, which cannot be used for SSL/TLS in Explicit Mode, the IMAP server MUST be configured to use SSL/TLS over port 143 otherwise we will default to an unsecured channel.

Users may use Implicit mode on port 993 only for SSL/TLS by default.

User must make sure that secure connections have the same certificate installed on both the JAMS Scheduler Server and IMAP Server and we must be able to update the certificate revocation list over the internet

When trying to execute a large number of jobs simultaneously, jobs may fail with the message:

"There are no child processes to wait for"

This happens when the job cannot allocate a Windows desktop. Each JAMS job has its own non-interactive desktop. The size of a desktop is defined in the "SharedSection" portion of the registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\SubSystems\Windows

This registry key value contains many entries, one of them is the SharedSection value. A typical SharedSection would be "SharedSection=1024,3072,512". The third value is the size in kilobytes of a non-interactive desktop.

Desktops are allocated from the Windows SessionView. The size of the SessionView is defined by the registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Memory Management\SessionViewSize

A typical value of this entry is 30 hex (48 decimal). This value is in megabytes.

If a user has a SessionViewSize of 48MB and a non-interactive desktop size of 512KB, in theory, the user could run 96 simultaneous jobs. But, Windows and other applications also need desktops, so the real number is less than that.

If users have jobs failing with "There are no child processes to wait for" users have three choices:

1. Increase the size of the SessionViewSize registry entry. This will require a reboot.
2. Decrease the size of the third value of SharedSection. This will require a reboot and may affect non-interactive applications that need a 512KB desktop.
3. Limit the number of simultaneous jobs. This can be done with a job limit on batch queues or with resources.

More information about Windows desktops can be found at:

Note that this applies to WIndows 2000, Windows Server 2003 and Windows XP. Windows Vista, Windows Server 2008 and WIndows 7 can dynamically adjust the size of SessionViewSize.

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