[erlang-questions] Possilbe Erlang memory fragmentation

Fred Hebert mononcqc@REDACTED
Mon Dec 7 20:30:31 CET 2015

On 12/07, linbo liao wrote:
>Our Erlang server looks have a serious memory leak, the VM memory usage is
>low but top is high.
>*# Fragmentation*
>I execute recon_alloc:fragmentation(current) and
>recon_alloc:fragmentation(max), find some allocator current usage is lower
>than max usage.
>*## Current usage*
>>      {{binary_alloc,0},
>>       [{sbcs_usage,1.0},
>>        {mbcs_usage,0.037804497612847224},
>>        {sbcs_block_size,0},
>>        {sbcs_carriers_size,0},
>>        {mbcs_block_size,178384},
>>        {mbcs_carriers_size,4718592}]},
>>      {{binary_alloc,2},
>>       [{sbcs_usage,2.0},
>>        {mbcs_usage,0.05326200786389803},
>>        {sbcs_block_size,0},
>>        {sbcs_carriers_size,0},
>>        {mbcs_block_size,4775112},
>>        {mbcs_carriers_size,89653248}]},
>>      {{binary_alloc,1},
>>       [{sbcs_usage,2.0},
>>        {mbcs_usage,0.0643930146188447},
>>        {sbcs_block_size,0},
>>        {sbcs_carriers_size,0},
>>        {mbcs_block_size,4456384},
>>        {mbcs_carriers_size,69206016}]},

Yeah, those are very, very low usage values on mbcs (<5%). Can you give 
information such as the average block size (also in recon_alloc), how 
long the node has been running, and so on?

All values for current and max are useful for these. Also if you could 
provide your allocator strategy that could be useful.

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