Windows Processes and Job Objects

When Windows creates a new process, it doesn’t create a parent / child relationship with the new process. This means a new “child” processes will continue running after the “parent” process has ended. Usually that’s what we want – but sometimes we want a way to link the parent and child process(es) together. For example, we might need to be able to stop a child process and any additional processes that child process might have started. Or we might want to restrict the amount of memory or CPU time the child processes can use.

A Windows job object allows you to:

1. Associate multiple processes with a single job, so you can control them as a group
2. Place restrictions on a job’s processes, including:

• Limit the maximum amount of memory for a job (or each process)
• Limit the maximum CPU time for a job (or each process)
• Limit the maximum number of processes in a job
• Set the priority class for the job’s processes
• Limit a job’s access to UI elements, including the clipboard, user handles, desktops, etc.
• Prevent a job’s processes from logging out, rebooting, or shutting down

Prior to v21, there hasn’t been a way to do this in a batch file. V21 now allows you to create and monitor Windows job objects with two new commands:

JOBS creates new Windows jobs and optionally attaches processes to a job. (You can also start a process in a job with the “START /job=jobname” option.) You can specify limits for a new or existing job, or display the current limit info for the job.

JOBMONITOR monitors activity and notifications for the specified job, including:

• End of job
• New process creation
• Process exit
• Job or process memory limits
• Job or process exceeded CPU time limits

(Note that due to obvious Windows security issues a process cannot change its own job limits.)

ANSI and Windows 10 Creators Update

Prior to Windows 10 Creators Update, Take Command and TCC had their own internal support for handling ANSI escape sequences (for cursor control and output colorization).  Because Windows 10 Creators Update now has its own built-in (and faster) ANSI in the Windows console, Take Command and TCC will use the Windows ANSI support if:

1. ANSI is disabled in the Take Command configuration (Tabs / Windows / ANSI colors), and
2. ANSI is enabled in the TCC configuration (OPTION / Windows / Colors / ANSI Colors)

(Note that due to as-yet-noexistent Windows APIs, Take Command unfortunately cannot support the 256 color or 24-bit color options available in the Windows 10 Linux Subsystem.)