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Date: -- (:)
From: Martin Jambon <m.jambon@i...>
Subject: [Caml-list] Memory leak
Hello,

Is it possible that non-negligible amounts of unreachable data are never
freed by the GC?

My program seems to waste memory, even with Gc.max_overhead set to 50 (or
even 0).
What should I do?

The program is written only in OCaml.
It has been tested using version 3.04 and last friday's working version
(3.04+9 (2002-04-04)).

No dangerous feature of the language is used except Marshal, I think.
The program may sequentially handle several gigabytes of marshaled data,
but doesn't crash and always produces correct results.

Example of Gc.stat (OCaml 3.04):

minor_words: 1746668652
promoted_words: 104792423
major_words: 232260045
minor_collections: 121
major_collections: 75727
heap_words: 250683392 (* bytes *)
heap_chunks: 941
live_words: 28221788
live_blocks: 4657360
free_words: 34443371
free_blocks: 772158
largest_free: 21914
fragments: 5689
compactions: 11

In this case, the size of the heap should stay below 10 MB. Here, it is
250 MB.
Removal of some parts of the program doesn't produce expected results
[...].


Comments in module Gc say [about Gc.finalise]:
   Some constant values can be heap-allocated but never deallocated
   during the lifetime of the program, for example a list of integer
   constants; this is also implementation-dependent.

How do I know if my program uses such permanent data?
Should I use Gc.finalise to look for missing deallocations?


Hoping I will get some help...
Thanks in advance,


Martin

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