[erlang-questions] Dangers of generating a large erlang module

Ivan uemlianin <>
Sun Sep 29 19:20:03 CEST 2013


Thanks! I think I'll try and head in that direction. I've had a few goes at other methods (db lookup etc) and they're much slower than this "dynamic hardcoding"). I'll sniff around for Core Erlang tutorials.

Best wishes

Ivan


--
festina lente


On 29 Sep 2013, at 17:48, Erik Søe Sørensen <> wrote:

> A thing which I discovered recently (in connection with mochiglobal) is that compiling code containing large binaries, or large amounts of binaries,  is quite memory-intensive. As I recall it, the numbers were ~64 bytes of RAM per byte in a binary metal; twice as much if on a 64 bit emulator.
> Which means that if you want to compile modules containing (in sum) multimegabyte binaries, doing so from Erlang source or from full Erlang AST is a no-go.  Iirc, it is feasible if starting from Core Erlang.
> /Erik
> 
> Den 29/09/2013 12.50 skrev "Ivan Uemlianin" <>:
>> Dear Anthony
>> 
>> Thanks for your comment.
>> 
>> Yes, that's exactly what the generated module is doing.  The generated module has a single function with many clauses like this:
>> 
>>     f(<<"trigger", Rest/binary) -> ...
>> 
>> This is why (as far as I can work out) the generated code has to be so big.
>> 
>> I prefer the idea of generating and loading code to, say, updating a database table, because it seems faster and less likely to lead to bottlenecks.
>> 
>> Best wishes
>> 
>> Ivan
>> 
>> 
>> On 29/09/2013 11:38, Anthony Ramine wrote:
>>> Hello Ivan,
>>> 
>>> Out of curiosity, what does it look like?
>>> 
>>> Pattern matching on literal values in Erlang is done with a binary search over the sorted list of patterns, I am not sure this would play well with your use case even if the compilation didn't bring the VM down.
>>> 
>>> Regards,
>>> 
>>> Le 29 sept. 2013 à 11:29, Ivan Uemlianin a écrit :
>>> 
>>>> All goes well on small test files, but the files I want to use IRL are relatively large --- around 120,000 lines.
>> 
>> -- 
>> ============================================================
>> Ivan A. Uemlianin PhD
>> Llaisdy
>> Speech Technology Research and Development
>> 
>>                     
>>                      www.llaisdy.com
>>                          llaisdy.wordpress.com
>>               github.com/llaisdy
>>                      www.linkedin.com/in/ivanuemlianin
>> 
>>                         festina lente
>> ============================================================
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