Re: [pbs-devel] [PATCH proxmox-backup] task tracking: improve pruning of reused-PID stale entries

[Hannes Laimer <h.laimer@proxmox.com>]

On 11/17/25 10:30, Fabian Grünbichler wrote:
> On November 17, 2025 9:58 am, Hannes Laimer wrote:
>> Keep entries only when check_process_running(pid) reports a
>> starttime equal to the stored one. This improves pruning of stale
>> entries for all PIDs (not just the current one) and aligns update
>> with the read path. Counting behavior and semantics are unchanged.
> 
> I don't think this is correct? the starttime comparison is only valid
> for the current process, an old process will almost certainly have a
> different starting time and we still want to keep its entry if it is
> still running..
> 

But not the same PID. This drops an entry only if the starttime for a 
pid in `/proc/<pid>/stat` and the tracking file don't match.
we can't have a reused pid with the old process not dead

hope I'm not missing something :P


> if we want to improve this, we would need to query the process starttime
> for all entries, and then compare, but that would make this more
> expensive..
> 
>>
>> Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>
>> ---
>> noticed while looking through recent proposed changes to the tracking
>> logic. this isn't a problem, but should keep the tracking file cleaner
>> and remove a match arm in the code
>>
>>   pbs-datastore/src/task_tracking.rs | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/pbs-datastore/src/task_tracking.rs b/pbs-datastore/src/task_tracking.rs
>> index 44a4522d..4fcbbaa4 100644
>> --- a/pbs-datastore/src/task_tracking.rs
>> +++ b/pbs-datastore/src/task_tracking.rs
>> @@ -114,8 +114,7 @@ pub fn update_active_operations(
>>               .iter_mut()
>>               .filter_map(
>>                   |task| match procfs::check_process_running(task.pid as pid_t) {
>> -                    Some(stat) if pid == task.pid && stat.starttime != task.starttime => None,
>> -                    Some(_) => {
>> +                    Some(stat) if stat.starttime == task.starttime => {
>>                           if pid == task.pid {
>>                               found_entry = true;
>>                               match operation {
>> -- 
>> 2.47.3
>>
>>
>>
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>>
>>
>>
> 
> 
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