Re: [Xen-devel] xenstored memory leak

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 06/07/16 14:55, Juergen Gross wrote:
> On 06/07/16 15:48, Andrew Cooper wrote:
>> On 06/07/16 08:31, Juergen Gross wrote:
>>> While testing some patches for support of ballooning in Mini-OS by using
>>> the xenstore domain I realized that each xl create/destroy pair would
>>> increase memory consumption in Mini-OS by about 5kB. Wondering whether
>>> this is a xenstore domain only effect I did the same test with xenstored
>>> and oxenstored daemons.
>>>
>>> xenstored showed the same behavior, the "referenced" size showed by the
>>> pmap command grew by about 5kB for each create/destroy pair.
>>>
>>> oxenstored seemed to be even worse in the beginning (about 6kB for each
>>> pair), but after about 100 create/destroys the value seemed to be
>>> rather stable.
>> Do you mean that after a while, you see oxenstored not leaking any
>> further memory, even with new domains being created?
> In my test: yes. I did:
>
> while true
> do
>   xl create minios.xl
>   sleep 3
>   xl shutdown minios
>   sleep 2
> done
>
> After about 200 iterations memory usage with oxenstored was stable. I
> stopped the loop after more than 1000 iterations.
>
>> Ocaml is a garbage collected languague, so you would expect the process
>> to get larger until the GC decides to kick in.
> Okay. This explains the pattern.
>
>>> Did anyone notice this memory leak before?
>> We have not encountered this in XenServer stress scenarios.
> You are using oxenstored, right? The real leak is in xenstored only.

Correct.

>
>> (It is entirely possible that this specific to something xl does which
>> Xapi doesn't.)
> I doubt that. I'm seeing the leak with the C-variant of xenstore, both
> as daemon and as stubdom.

Right, and we haven't used C xenstored in the last decade.

~Andrew

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