[Caml-list] Re: Memory fragmentation

[SerP <serp256@gmail.com>]

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Ocaml 3.12.0., Lwt 2.3.1
On Apr 20, 2012 7:12 PM, "SerP" <serp256@gmail.com> wrote:

> Hi!
> We have developped a daemon on ocaml using the lwt lib(libev). It
> processes about 800 requests per second, but it increases to 2 Gb in memory
> for a hour of work. We have studied the problem for a long time, using
> mtrace, mallinfo and other tools, and we tried to change GC params. We
> found out that setting up GC.minor_heap_size=10Mb а
> major_heap_increment=2Мb will make the daemon grow slower. mallinfо shows
> that the memory (1,5G) is allocated using mmap (blkhd field in mallinfo
> struct) and arena size - about 20M In this case, first calls of GC.compact
> compress the daemon to 200 Mb (live -110Mb) , and mallinfo show decreasing
> of total size of memory allocated by mmap. The daemon keeps growing, but it
> allocates the memory to arena (using brk), and calls of GC.compact leads to
> decrease of heap_bytes to 200M, but arena size (1.5 Gb) does not decrease,
> just doing less uordblks and more fordblks (fileds I.e., after first calls
> of GC.compact, the daemon starts using brk much more than mmap, and cant
> memory given back to the system.
>
> If Gc.allocation_policy is first fit, memory usage is stable, and it's
> grow very little, but worked very slowly.
>
> Any suggestions are very welcome. Thanks
>

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