Debugging GC warning on repeated allocation of very large block

[Santiago Palladino]

Hi all!

I'm doing some heavy data-processing tests in Crystal (in particular, github.com/mverzilli/crystalla) and I'm getting this repeated warning from the GC:

GC Warning: Repeated allocation of very large block (appr. size 39493632):

May lead to memory leak and poor performance.

Any ideas on how to debug this, or find the source of this alloc?

Thanks!

[Ary Borenszweig]

That happens when you allocate a lot of memory and don't free it. For example this code triggers the same warning:

~~~

x = [] of Array(Int32)

loop do

  x << Array.new(10_000_000, 0)

end

~~~

Boehm GC has a callbacks for warnings, I tried using it and printing the call stack but it's not useful. Can you show the code that's causing the warning?

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Ary Borenszweig         Manas Technology Solutions
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[Santiago Palladino]

I found a possible cause, but it is still throwing the warning at random runs. I’ll try to narrow it down and let you know. Thanks!

-- 
Santiago Palladino 
Manas Technology Solutions
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[us.phone] 312.612.1050
[email] spall...@manas.com.ar
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