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 Fri,  5 Jun 2020 10:14:56 +0300 (MSK)
Date: Fri, 5 Jun 2020 10:14:43 +0300
From: Sergey Kaplun <skaplun@tarantool.org>
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Subject: Re: [Tarantool-patches] [PATCH v2] lua: remove excess Lua call from
 table encoding
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To: Sergey Ostanevich <sergos@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org, Vladislav Shpilevoy <v.shpilevoy@tarantool.org>

Hi!

It's a little bit complicated to find a good test that shows the
difference of behaviour. AFAIK there is only one case when we can face
with OOM error or so on - reallocating of Lua stack. But it can happen
with old version too (when we push cfunction, table or lightuserdata at
Lua stack before pcall). Now instead three values we push at Lua stack
only two (Lua function from metatable and table itself if serializing
function exists) before pcall. So with this patch the probability of
raising OOM error should be decreased.

Of course we can check it with an eror injection, but it can be catched
with old behaviour too. It will be nice if you can provide any idea of
this kind of test to check this.

On 02.06.20, Sergey Ostanevich wrote:
> Hi!
> 
> Thanks for the patch!
> 
> Still I would like to see some tests - perhaps with errinj to emulate
> OOM or some other case that trigger the 'excess protected frame' need.
> So that after your changes it still passes.
> 
> Regards,
> Sergos
> 

-- 
Best regards,
Sergey Kaplun