[Python-Dev] MemoryError... how much memory?

[Nick Coghlan]

On Thu, Oct 28, 2010 at 8:00 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> Facundo Batista <facundobatista at gmail.com> writes:
>
>> On Wed, Oct 27, 2010 at 12:05 PM, Benjamin Peterson <benjamin at python.org> wrote:
>>
>> > Isn't this usually when you do something like [None]*2**300? In that
>> > case, wouldn't you know how much memory you're requesting?
>>
>> It could happen on any malloc. It depends on how much you have free.
>
> It also depends on how much is being requested. The caller knows that
> amount, surely?

For a server process, the MemoryError in the log won't always have the
context information showing what the values were in the calling
frames. The idea behind Facundo's request is similar to the reason why
we print the type names in a lot of TypeErrors.

If you see MemoryError (5 bytes), the things you go looking for are
very different from those you look for when you see MemoryError(1
gajillion bytes). (i.e. for the former, you look for a memory or other
resource leak, for the latter, you look for the reason your code is
trying to get 1 gajillion bytes from the OS). If a long-lived server
isn't crashing but is still getting MemoryError occasionally, problems
with specific oversized requests are much more likely than a general
resource leak (as those usually bring the whole process down
eventually).

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia