[gambit-list] Memory leak (?) using `c-define`d functions from foreign release functions.

Mikael mikael.rcv at gmail.com
Mon Dec 30 12:56:05 EST 2013


What's the behvior if you allocate 1 000 000 instead, is the problem
amplified proportionally?


2013/12/30 Estevo <euccastro at gmail.com>

> It seems that's not the problem.  Refcount is 0, yet the object is kept
> alive.
>
> Running the modified script below, I get the following:
>
> [BEGIN OUTPUT]
>
> p is #<point* #2 0x12309a0>
> release-point called on serial 3
> found in object table as: #<void* #3 0x12309a0>
>
> *** after GC:
> foreign serial is 3, corresponding to #<void* #3 0x12309a0>, a
> mem-allocated still object with reference count == 0
> Bye.
>
> [END OUTPUT]
>
>
> ;--------------------------------------------------------------------------------------
>
>
> (c-declare "struct { int x; int y; } point;")
>
> (define no-err ((c-lambda () scheme-object "___result =
> ___FIX(___NO_ERR);")))
>
> (define ptr-serial #f)
>
>
> (c-define (release-point ptr)
>           ((pointer void)) scheme-object "scm_release_point" ""
>   (set! ptr-serial (object->serial-number ptr))
>   (println "release-point called on serial " ptr-serial)
>   (println "found in object table as: "
>     (table-ref ##serial-number-to-object-table ptr-serial 'not-there))
>
>   ((c-lambda ((pointer void)) void "___release_rc") ptr)
>   no-err)
>
> (c-define-type point (type "point" (point*) "scm_release_point"))
>
>
> (define p ((c-lambda () point
>              "___result_voidstar = ___EXT(___alloc_rc)(sizeof(point));")))
>
> (println "p is " p)
>
> (set! p #f)
>
> (##gc)
>
> (newline)
> (println "*** after GC:")
> (print "foreign serial is " ptr-serial)
> (print ", corresponding to "
>   (table-ref ##serial-number-to-object-table ptr-serial 'not-there))
>
> (print ", a "
>          (if ((c-lambda (scheme-object) bool "___result =
> ___MEM_ALLOCATED(___arg1);")
>               (table-ref ##serial-number-to-object-table ptr-serial
> 'not-there))
>            ""
>            "not")
>          " mem-allocated")
>
> (print " "
>   ((c-lambda (scheme-object) char-string "___result =
> ___HD_TYP(___BODY(___arg1)[-1]) == ___STILL ? \"still\" : \"something
> else\";")
>    (table-ref ##serial-number-to-object-table ptr-serial 'not-there)))
>
> (println " object with reference count == "
>          ((c-lambda (scheme-object) int "___result =
> ___UNTAG(___arg1)[___BODY_OFS - 6 + 1];")
>           (table-ref ##serial-number-to-object-table ptr-serial
> 'not-there)))
>
> (println "Bye.")
>
>
>
>
> On Mon, Dec 30, 2013 at 10:09 AM, Mikael <mikael.rcv at gmail.com> wrote:
>
>> Refcount is 1 by default so you need to decrease it for it to GFC?
>>
>> Allocate a zillion points and check the two respective ways.
>>
>>
>> 2013/12/29 Estevo <euccastro at gmail.com>
>>
>>>  Here's a more realistic version of what I was trying to do:
>>>
>>> (c-declare "struct { int x; int y; } point;")
>>>
>>> (define no-err ((c-lambda () scheme-object "___result =
>>> ___FIX(___NO_ERR);")))
>>>
>>> (c-define (release-point ptr)
>>>           ((pointer void)) scheme-object "scm_release_point" ""
>>>   (println "release-point called")
>>>   ((c-lambda ((pointer void)) void "___release_rc") ptr)
>>>   no-err)
>>>
>>> (c-define-type point (pointer "point" (point*) "scm_release_point"))
>>>
>>>
>>> (define p ((c-lambda () point
>>>              "___result_voidstar =
>>> ___EXT(___alloc_rc)(sizeof(point));")))
>>>
>>> (println "p is " p)
>>> (set! p #f)
>>>
>>> (##gc)
>>>
>>> (println "Bye.")
>>>
>>> valgrind's complaint is different in this one.  What is leaked here
>>> (again, unless valgrind is giving me a false positive) seems to be the
>>> Scheme representation of `ptr`:
>>>
>>> ==9631== Memcheck, a memory error detector
>>> ==9631== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
>>> ==9631== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright
>>> info
>>> ==9631== Command: ./test-c-define
>>> ==9631==
>>> p is #<point* #2 0x5c04620>
>>> release-point called
>>> Bye.
>>> ==9631==
>>> ==9631== HEAP SUMMARY:
>>> ==9631==     in use at exit: 158 bytes in 2 blocks
>>> ==9631==   total heap usage: 154 allocs, 152 frees, 4,247,245 bytes
>>> allocated
>>> ==9631==
>>> ==9631== 158 (87 direct, 71 indirect) bytes in 1 blocks are definitely
>>> lost in loss record 2 of 2
>>> ==9631==    at 0x4C2B6CD: malloc (in
>>> /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>>> ==9631==    by 0x4C7DC6: ___alloc_mem (os_base.c:185)
>>> ==9631==    by 0x4B6905: alloc_mem_aligned (mem.c:452)
>>> ==9631==    by 0x4B77A7: alloc_scmobj_still (mem.c:1245)
>>> ==9631==    by 0x4B78B1: ___alloc_scmobj (mem.c:1285)
>>> ==9631==    by 0x4C3DEE: ___POINTER_to_SCMOBJ (c_intf.c:5154)
>>> ==9631==    by 0x4B1C88: scm_release_point (test-c-define.c:665)
>>> ==9631==    by 0x4C1027: ___release_foreign (c_intf.c:1713)
>>> ==9631==    by 0x4BAEA4: free_unmarked_still_objs (mem.c:3271)
>>> ==9631==    by 0x4BD472: ___garbage_collect (mem.c:4698)
>>> ==9631==    by 0x4E4357: ___H__20___kernel (_kernel.c:9170)
>>> ==9631==    by 0x4B49B2: trampoline (setup.c:1618)
>>> ==9631==
>>> ==9631== LEAK SUMMARY:
>>> ==9631==    definitely lost: 87 bytes in 1 blocks
>>> ==9631==    indirectly lost: 71 bytes in 1 blocks
>>> ==9631==      possibly lost: 0 bytes in 0 blocks
>>> ==9631==    still reachable: 0 bytes in 0 blocks
>>> ==9631==         suppressed: 0 bytes in 0 blocks
>>> ==9631==
>>> ==9631== For counts of detected and suppressed errors, rerun with: -v
>>> ==9631== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
>>>
>>>
>>>
>>> On Thu, Dec 26, 2013 at 11:23 PM, Estevo <euccastro at gmail.com> wrote:
>>>
>>>> Valgrind reports Gambit is leaking a "sfun stack marker" if I call,
>>>> from a foreign release function, another function defined with `c-define`.
>>>> The code below is about the most innocent looking thing I could come up
>>>> with.
>>>>
>>>> Doesn't Gambit like c-define functions called within release functions,
>>>> or is Valgrind giving me a false positive here (as it is wont to do quite
>>>> often.)
>>>>
>>>> ; ~/gambit-dbg/bin/gsc -exe -cc-options -g test-c-define.scm &&
>>>> valgrind --leak-check=full ./test-c-define
>>>>
>>>> (c-declare #<<c-declare-end
>>>>
>>>> typedef struct { int x; int y; } point;
>>>>
>>>> void scm_release_point(unsigned long);
>>>>
>>>> ___SCMOBJ c_release_point(void *ptr) {
>>>>     scm_release_point((unsigned long)ptr);
>>>>     ___EXT(___release_rc)(ptr);
>>>>     return ___FIX(___NO_ERR);
>>>> }
>>>>
>>>> c-declare-end
>>>> )
>>>>
>>>> (c-define (release-point ptr) (unsigned-long) void "scm_release_point"
>>>> ""
>>>>   (println "release-point called"))
>>>>
>>>> (c-define-type point (pointer "point" (point*) "c_release_point"))
>>>>
>>>> (define p ((c-lambda () point
>>>>                  "___result_voidstar =
>>>> ___EXT(___alloc_rc)(sizeof(point));")))
>>>>
>>>> (println "p is " p)
>>>> (set! p #f)
>>>>
>>>> (##gc)
>>>> ; for good measure...
>>>> (##gc)
>>>> (##gc)
>>>>
>>>> (println "Bye.")
>>>>
>>>>
>>>> valgrind --leak-check=full ./test-c-define
>>>> ==16301== Memcheck, a memory error detector
>>>> ==16301== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et
>>>> al.
>>>> ==16301== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright
>>>> info
>>>> ==16301== Command: ./test-c-define
>>>> ==16301==
>>>> p is #<point* #2 0x5c04640>
>>>> release-point called
>>>> Bye.
>>>> ==16301==
>>>> ==16301== HEAP SUMMARY:
>>>> ==16301==     in use at exit: 71 bytes in 1 blocks
>>>> ==16301==   total heap usage: 153 allocs, 152 frees, 4,247,198 bytes
>>>> allocated
>>>> ==16301==
>>>> ==16301== 71 bytes in 1 blocks are definitely lost in loss record 1 of 1
>>>> ==16301==    at 0x4C2B6CD: malloc (in
>>>> /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>>>> ==16301==    by 0x4C922E: ___alloc_mem (os_base.c:185)
>>>> ==16301==    by 0x4B7DB5: alloc_mem_aligned (mem.c:452)
>>>> ==16301==    by 0x4B8C57: alloc_scmobj_still (mem.c:1245)
>>>> ==16301==    by 0x4B8D61: ___alloc_scmobj (mem.c:1285)
>>>> ==16301==    by 0x4B8E44: ___make_vector (mem.c:1362)
>>>> ==16301==    by 0x4C677B: ___make_sfun_stack_marker (c_intf.c:6452)
>>>> ==16301==    by 0x4B359E: scm_release_point (test-c-define.c:139)
>>>> ==16301==    by 0x4B354B: c_release_point (test-c-define.c:130)
>>>> ==16301==    by 0x4C24D7: ___release_foreign (c_intf.c:1713)
>>>> ==16301==    by 0x4BC354: free_unmarked_still_objs (mem.c:3271)
>>>> ==16301==    by 0x4BE922: ___garbage_collect (mem.c:4698)
>>>> ==16301==
>>>> ==16301== LEAK SUMMARY:
>>>> ==16301==    definitely lost: 71 bytes in 1 blocks
>>>> ==16301==    indirectly lost: 0 bytes in 0 blocks
>>>> ==16301==      possibly lost: 0 bytes in 0 blocks
>>>> ==16301==    still reachable: 0 bytes in 0 blocks
>>>> ==16301==         suppressed: 0 bytes in 0 blocks
>>>> ==16301==
>>>> ==16301== For counts of detected and suppressed errors, rerun with: -v
>>>> ==16301== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
>>>>
>>>
>>>
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>>> Gambit-list mailing list
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>>>
>>>
>>
>
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