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Hadoop >> mail # user >> Re: How are 'PHYSICAL_MEMORY_BYTES' and 'VIRTUAL_MEMORY_BYTES' calculated?


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Re: How are 'PHYSICAL_MEMORY_BYTES' and 'VIRTUAL_MEMORY_BYTES' calculated?
If a program terminates normally, i would assume its memory usage close to
zero or at least very small, because the program release most memory it was
allocated. That would mean all jobs in Hadoop had very small memory usage,
because only the last point was measured. Actually, this is not case. We
can see some programs with several G memory usage. Is that means at the end
of the program it still hold several G memory? I am still confused.

Regards,
Qi
On Fri, Jul 12, 2013 at 1:51 PM, Shahab Yunus <[EMAIL PROTECTED]>wrote:

> As Vinod Kumar Vavilapalli they are indeed snapshots in point and time. So
> they are neither the peak usage from the whole duration of the job, nor
> cumulative aggregate that increases over time.
>
> Regards,
> Shahab
>
>
> On Fri, Jul 12, 2013 at 4:47 PM, hadoop qi <[EMAIL PROTECTED]> wrote:
>
>> Thanks for the response. So they represent the total physical memory
>> (virtual memory) has been allocated to the job (e.g., from heap and stack)
>> during its entire life time? I am still confused how to get the cumulative
>> number from /proc/meminfo. I think from /proc/meminfo we can only get the
>> memory usage of a  process in a particular time point (looked like a
>> snapshot of the status of the process). If these numbers are added, the sum
>> would be much more than memory allocated to the program.
>>
>>
>> On Fri, Jul 12, 2013 at 6:47 AM, Shahab Yunus <[EMAIL PROTECTED]>wrote:
>>
>>> I think they are cumulative but per task.
>>>
>>> Physical memory bytes
>>> (PHYSICAL_MEMORY_BYTES)
>>> The physical memory being used by a task in bytes, as reported by
>>> /proc/meminfo.
>>> Virtual memory bytes
>>> (VIRTUAL_MEMORY_BYTES)
>>> The virtual memory being used by a task in bytes, as reported by
>>> /proc/meminfo.
>>>
>>> This is from the Definitive Guide book. Page 260.
>>>
>>> Regards,
>>> Shhab
>>>
>>>
>>> On Thu, Jul 11, 2013 at 12:47 PM, hadoop qi <[EMAIL PROTECTED]>wrote:
>>>
>>>> Hello,
>>>>
>>>> I am wondering how memory counters  'PHYSICAL_MEMORY_BYTES'  and
>>>> 'VIRTUAL_MEMORY_BYTES'  are calculated? They are peaks of memory usage or
>>>> cumulative usage?
>>>>
>>>> Thanks for help,
>>>>
>>>
>>>
>>
>