How to RESTART a specific command if it fails in Windows Powershell?

Question

In a ps1 file I start 2 separate processes like so: As you can see the only difference is the CPU affinity.

$Process1 = Start-Process -FilePath 'C:\Windows\system32\notepad.exe' -PassThru
$Process1.ProcessorAffinity = 65535
$Process1.PriorityClass = 'RealTime'

$Process2 = Start-Process -FilePath 'C:\Windows\system32\notepad.exe' -PassThru
$Process2.ProcessorAffinity = 4294901760
$Process2.PriorityClass = 'RealTime'

Sometimes, randomly, one of the 2 processes fails with: Problem Event Name: BEX64

It is essential that the process is restarted immediately when a failure like this happens. So I am faced with this problem.

Can I monitor within the PS1 file the 2 processes and if one fails to restart it? The monitoring process must be able to distinguish which of the 2 processes has failed, so that the correct affinity is used to restart it.

If you have a solution involving windows batch script please visit How to RESTART a specific command if it fails in Windows Batch file?

Thanks

Process.ProcessorAffinity is a bitmask representing the CPUs, so using decimal for it makes zero sense. Use $Process1.ProcessorAffinity = 0xFFFF instead of 65535 — phuclv
– phuclv, Commented Jul 14, 2021 at 0:44
actually powershell has asked me to use IntPtr and accepts these values without issue. I am using them because it would not accept 0x00000000FFFF0000 — conanDrum
– conanDrum, Commented Jul 14, 2021 at 0:52
Who said that 0x00000000FFFF0000 isn't accepted? Unless your CPU has fewer than 32 CPUs. 65535 = 0xFFFF, not 0x00000000FFFF0000. To powershell both decimal and hex literals represent the same value but to human readers the decimal value doesn't make sense — phuclv
– phuclv, Commented Jul 14, 2021 at 1:31

Doug Maurer · Accepted Answer · 2021-07-14 01:07:24Z

3

$Process1 = Start-Process -FilePath 'C:\Windows\system32\notepad.exe' -PassThru
$Process1.ProcessorAffinity = 1
$Process1.PriorityClass = 'RealTime'
Write-Host Process ID $process1.Id started with CPU affinity $Process1.ProcessorAffinity

$Process2 = Start-Process -FilePath 'C:\Windows\system32\notepad.exe' -PassThru
$Process2.ProcessorAffinity = 2
$Process2.PriorityClass = 'RealTime'
Write-Host Process ID $process2.Id started with CPU affinity $Process2.ProcessorAffinity

while($true){
    foreach($process in $Process1,$Process2){
        if($process.hasexited){

            Write-Host "Process ID $($process.id) has exited, restarting."
            $priority = $process.PriorityClass
            $affinity = $process.ProcessorAffinity
            if($newprocess = $process.Start()){
                Write-Host Successfully restarted process ID $process.Id with CPU affinity $process.ProcessorAffinity
                $process.PriorityClass = $priority
                $process.ProcessorAffinity = $affinity
                Write-Host Priority Class set back to $process.PriorityClass
                Write-Host Process affinity set back to $process.ProcessorAffinity
            }
        }
    }
    Start-Sleep -Milliseconds 500
}

edited Jul 14, 2021 at 1:07

answered Jul 13, 2021 at 19:44

Doug Maurer

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5 Comments

conanDrum Over a year ago

Good answer. only problem is that when you restart the process, the affinity and priority are not retained. correct?

Doug Maurer Over a year ago

The affinity seemed to be the same in my tests but they were very basic/quick.

Doug Maurer Over a year ago

@conanDrum It seems you are correct about the PriorityClass, I've updated my answer. Thanks!

conanDrum Over a year ago

I get this:Process ID 9744 started with CPU affinity 65535 Process ID 19312 started with CPU affinity 4294901760 Process ID 19312 has exited, restarting. Successfully restarted as process ID 16120 with CPU affinity 4294967295 Process ID 16120 has exited, restarting. Successfully restarted as process ID 20084 with CPU affinity 4294967295

conanDrum Over a year ago

Affinity is always 4294967295

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