Re: ZODB eating CPU but RAM is free

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On Saturday, December 15, 2018 at 8:30:16 AM UTC-8, Jim Fulton wrote:
>
>
>
> On Fri, Dec 14, 2018 at 9:54 PM Vlad Oles <[email protected]=20
> <javascript:>> wrote:
>
>> On Wednesday, July 19, 2017 at 9:54:05 AM UTC-7, Jim Fulton wrote:
>>>
>>>
>>> One thing to understand is that ZODB doesn't limit memory usage. =20
>>> Ghostifies objects to meet memory settings at certain times like=20
>>> transaction boundaries and when asked to explicitly.  So a transaction =
that=20
>>> loads a lot of objects can grow ram without bound.  This is why=20
>>> applications that load *lots* of objects should explicitly reduce cache=
=20
>>> size by calling _p_jar.cacheGC() occasionally.=20
>>>
>>
>> Does it mean that after a database is finalized (no more writing and thu=
s=20
>> transactions), there is no way to bound its RAM cache size other than=20
>> manually resetting cache (via cacheGC() or cacheMinimize()) after every =
N=20
>> reads?
>>
>
> Define finalized.
>
> When a transaction is committed or a connection closed, the connection's=
=20
> cache is reduced to it's target size. When a database is closed, the=20
> connections and their memory is freed. (If there are cycles, the Python=
=20
> garbage collection may take some time to deal with them.)
>

By "finalized" I meant the connection is still open but no more=20
transactions are being commited, so the database is used only for reads.

I think I can confirm my initial assumption from your answer though =E2=80=
=94 the=20
target cache size configuration is not going to be applied automatically in=
=20
this scenario, and I'll have to free database cache manually by caling=20
cacheMinimize().

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<div dir=3D"ltr">On Saturday, December 15, 2018 at 8:30:16 AM UTC-8, Jim Fu=
lton wrote:<blockquote class=3D"gmail_quote" style=3D"margin: 0;margin-left=
: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir=3D"ltr"><b=
r><br><div class=3D"gmail_quote"><div dir=3D"ltr">On Fri, Dec 14, 2018 at 9=
:54 PM Vlad Oles &lt;<a href=3D"javascript:" target=3D"_blank" gdf-obfuscat=
ed-mailto=3D"5QFpmg4jCQAJ" rel=3D"nofollow" onmousedown=3D"this.href=3D&#39=
;javascript:&#39;;return true;" onclick=3D"this.href=3D&#39;javascript:&#39=
;;return true;">[email protected]</a>&gt; wrote:<br></div><blockquote cl=
ass=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid=
 rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">On Wednesday, July 19,=
 2017 at 9:54:05 AM UTC-7, Jim Fulton wrote:<blockquote class=3D"gmail_quot=
e" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204)=
;padding-left:1ex"><div dir=3D"ltr"><br><div><div class=3D"gmail_quote"><di=
v>One thing to understand is that ZODB doesn&#39;t limit memory usage.=C2=
=A0 Ghostifies objects to meet memory settings at certain times like transa=
ction boundaries and when asked to explicitly.=C2=A0 So a transaction that =
loads a lot of objects can grow ram without bound.=C2=A0 This is why applic=
ations that load <b>lots</b> of objects should explicitly reduce cache size=
 by calling <font face=3D"monospace, monospace">_p_jar.cacheGC()</font> occ=
asionally. <br></div></div></div></div></blockquote><div><br></div><div>Doe=
s it mean that after a database is finalized (no more writing and thus tran=
sactions), there is no way to bound its RAM cache size other than manually =
resetting cache (via cacheGC() or cacheMinimize()) after every N reads?</di=
v></div></blockquote><div><br></div><div>Define finalized.</div><div><br></=
div><div>When a transaction is committed or a connection closed, the connec=
tion&#39;s cache is reduced to it&#39;s target size. When a database is clo=
sed, the connections and their memory is freed. (If there are cycles, the P=
ython garbage collection may take some time to deal with them.)</div></div>=
</div></blockquote><div><br></div><div>By &quot;finalized&quot; I meant the=
 connection is still open but no more transactions are being commited, so t=
he database is used only for reads.</div><div><br></div><div>I think I can =
confirm my initial assumption from your answer though =E2=80=94 the target =
cache size configuration is not going to be applied automatically in this s=
cenario, and I&#39;ll have to free database cache manually by caling cacheM=
inimize().<br></div></div>

<p></p>

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