Re: [go-nuts] Huge map[string]*Object and GC where *Object is from sync.Pool

[Peter Mogensen]

On 09/28/2018 08:17 AM, Peter Mogensen wrote:
> 
> 
> On 09/28/2018 03:04 AM, keith.rand...@gmail.com wrote:
>> Objects returned by Get() are not special in any way. They will be GCd
>> just like an object returned by new(). In fact, they will often be just
>> a new()'d object.
>> There is no association of such an object with the pool.  A pool is just
>> a fancy free list. Get might return a previously Put'd object instead of
>> a new() one.
>>
>> Your scheme is unsafe. Storing a *Object as a uintptr means the
>> underlying Object will be collected out from under your map.
> 
> Ok... thanks... I guess I might have made the wrong assumption about
> when objects returned from pool.Get() are subject to garbage collection.
> 


However... (it's early here, so I forgot).

Of course the uintptr entries in the map is not the only reference to
the objects. In order to properly clean up there will be another
datastructure holding (say) a linked list of the objects.

For instance... if the map is only used as index to a huge database,
where the objects are actually stored in a priority queue to, say,
implement TTL or LRU.

So, there would always be another reference to the objects preventing
them for being garbage collected.

/Peter

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