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Editorial Team
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Asked: 2026-06-03T02:54:32+00:00

In .NET processor affinity and priority class for all threads and child processes can

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In .NET processor affinity and priority class for all threads and child processes can be set using Process.ProcessorAffinity and Process.PriorityClass properties. Using a job object it seems that the same can be set using JOB_OBJECT_LIMIT_AFFINITY and JOB_OBJECT_LIMIT_PRIORITY_CLASS flags.

So, what’s the difference between setting certain limitations like the above on a job object vs a process?

EDIT: Once I set the limits on the job object to something lower, a low-priveleged process can still overwrite them. Does it mean the job object limits are not reinforced? How can I restrict the low-priveleged account/process from overwriting them?

What is set:


JOBOBJECT_BASIC_LIMIT_INFORMATION jobBasicInfo = {0};
jobBasicInfo.LimitFlags = JOB_OBJECT_LIMIT_AFFINITY;
jobBasicInfo.Affinity = (ULONG_PTR) (1);  // affinitize to processor 1
jobBasicInfo.LimitFlags = JOB_OBJECT_LIMIT_SCHEDULING_CLASS;
jobBasicInfo.SchedulingClass = 4;         // below normal priority class
SetInformationJobObject( hJob,
      JobObjectBasicLimitInformation,
      &jobBasicInfo,
      sizeof(jobBasicInfo));

How it is overriden by a low-priveleged process:


Process process = Process.GetCurrentProcess();
process.PriorityClass = ProcessPriorityClass.High;
// all processors mask
process.ProcessorAffinity = new IntPtr((int)Math.Pow(2, Environment.ProcessorCount) - 1);
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1 Answer

  1. Editorial Team

    There is one big difference and some special cases. The big difference is that limits on the job object are just that: limits, while setting e.g. process priority always has an immediate effect. It’s not the same to limit the process priority to high (job object) and to set it to high (PriorityClass). The special cases arise when a process trying to give itself greater leeway than the job object allows; in which case the related API calls return success but actually do nothing, which is not the normal behavior.

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