Re: Understanding memory usage
| От | Damiano Albani |
|---|---|
| Тема | Re: Understanding memory usage |
| Дата | |
| Msg-id | CAKys9521rbsAVDk+h2xc2fdNs9-XXRuFJJEGh7ozc6MELU+m1w@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Understanding memory usage (Daniele Varrazzo <daniele.varrazzo@gmail.com>) |
| Ответы |
Re: Understanding memory usage
|
| Список | psycopg |
Hello,
On Tue, Oct 29, 2013 at 12:23 AM, Daniele Varrazzo <daniele.varrazzo@gmail.com> wrote:
By the way, I've re-run my tests but focused on the VmRSS metric, which represents how much actual physical memory is used by the process.
--
Damiano Albani
On Tue, Oct 29, 2013 at 12:23 AM, Daniele Varrazzo <daniele.varrazzo@gmail.com> wrote:
Because the result is returned to the client as the response for the
query and is stored inside the cursor. fetch*() only return it to
Python.
So why does calling "fetch*()" uses additional memory then? Does it copy the data returned from the database?
By the way, I've re-run my tests but focused on the VmRSS metric, which represents how much actual physical memory is used by the process.
And I got the same behavior, that is almost no memory is reclaimed after having fetched a large number of rows.
For instance, if I fetch 2 millions small rows, memory usage peaks around 500 MB and then only lowers to ~ 450 MB after data is freed.
On the other hand, fetching 100 large rows amounts to a 3 GB peak, which subsequently falls back to 10 MB.
So is it a problem related to Psycopg itself or rather how Python handles memory in general?
Regards,
Damiano Albani
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