[SCIP] releasing variables

James Cussens james.cussens at york.ac.uk
Thu May 4 11:10:22 CEST 2017 

Dear Marc,

Thanks for your help. It turned out that my problem was that I was trying
to release the same variable twice due to having stored (a pointer to ) it
in
two different places.

The page on memory management was very helpful. By compiling
with NOBLKMEM=true NOBUFMEM=true NOBLKBUFMEM=true and using valgrind
I found two memory leaks I didn't even know I had!

James

On 22 April 2017 at 01:03, Marc Pfetsch <pfetsch at mathematik.tu-darmstadt.de>
wrote:

>
>
> Dear James,
>
> here are my thoughts about your issue: Capturing and releasing variables
> (and constraints) is the way SCIP handles a "smart pointer" via memory
> counts. Each time a variable is captured, the counter is increased by 1.
> Each time a variable is released the counter is decreased by 1. One the
> number reaches 0, the memory is actually freed. This should explain the
> message a bit.
>
> Moreover, not that due to the internal data structures of SCIP, the
> messages concerning the positions at which the memory was allocated are
> not accurate. It just shows that some memory has not been freed.
>
> The most common problem is that transformed and original variables are
> counted separately. Can you please check whether you are releasing the
> "right" version? I might also help to check the time within the solution
> process at which you are releasing the variables. Possibly, you release
> the variables before (or free the memory).
>
> Moreover, if you are on a Linux system you can try valgrind toghether
> with the makefile option "NOBLKBUFMEM=true", see
> http://scip.zib.de/doc/html/MEMORY.php (near the bottom).
>
> I hope that this helps ...
>
> Best
>
> Marc
>
>
>
> On 20.04.2017 11:30, James Cussens wrote:
> > I am having trouble working out when/how to release variables.
> >
> > I have SCIP variables 'inside' my probdata. If I don't release them all
> > in my SCIP_DECL_PROBDELORIG function I get the following (but only in
> > OPT=dbg mode):
> >
> > ....
> > WARNING: Original variable <edge#TbOrCa#XRay> not released when freeing
> > SCIP. Consider releasing variable first.
> > [src/blockmemshell/memory.c:2503] ERROR: 320 bytes (4 elements of size
> > 80) not freed. First Allocator: src/scip/cons_pseudoboolean.c:424
> > [src/blockmemshell/memory.c:2503] ERROR: 768 bytes (12 elements of size
> > 64) not freed. First Allocator: src/scip/cons_nonlinear.c:9476
> > [src/blockmemshell/memory.c:2503] ERROR: 1952 bytes (61 elements of size
> > 32) not freed. First Allocator: src/nlpi/expr.c:11977
> > [src/blockmemshell/memory.c:2503] ERROR: 40584 bytes (89 elements of
> > size 456) not freed. First Allocator: src/scip/var.c:1900
> > [src/blockmemshell/memory.c:2503] ERROR: 2256 bytes (94 elements of size
> > 24) not freed. First Allocator: src/scip/cons_nonlinear.c:9463
> > [src/blockmemshell/memory.c:2503] ERROR: 28480 bytes (178 elements of
> > size 160) not freed. First Allocator: src/scip/cons_linear.c:533
> > [src/blockmemshell/memory.c:2503] ERROR: 304 bytes (19 elements of size
> > 16) not freed. First Allocator: src/nlpi/expr.c:11977
> > [src/blockmemshell/memory.c:2503] ERROR: 8 bytes (1 elements of size 8)
> > not freed. First Allocator: src/scip/cons_bounddisjunction.c:3109
> > [src/blockmemshell/memory.c:2521] ERROR: 74672 bytes not freed in total.
> >
> > Note that I do not use most of the constraint handlers mentioned above,
> > e.g I do not use cons_pseudoboolean,
> >
> >
> > When I do release them all I get the following:
> > ...
> > gobnilp: src/scip/var.c:2663: varFree: Assertion `(*var)->probindex ==
> > -1' failed.
> > Aborted (core dumped)
> >
> >
> > Here's the gdb backtrace for that:
> > ...
> > gobnilp: src/scip/var.c:2663: varFree: Assertion `(*var)->probindex ==
> > -1' failed.
> >
> > Program received signal SIGABRT, Aborted.
> > 0x00007ffff5db5428 in __GI_raise (sig=sig at entry=6) at
> > ../sysdeps/unix/sysv/linux/raise.c:54
> > 54../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
> > (gdb) bt
> > #0  0x00007ffff5db5428 in __GI_raise (sig=sig at entry=6) at
> > ../sysdeps/unix/sysv/linux/raise.c:54
> > #1  0x00007ffff5db702a in __GI_abort () at abort.c:89
> > #2  0x00007ffff5dadbd7 in __assert_fail_base (fmt=<optimised out>,
> > assertion=assertion at entry=0x17ca38c "(*var)->probindex == -1",
> > file=file at entry=0x17c8e60 "src/scip/var.c", line=line at entry=2663,
> >     function=function at entry=0x17d2e68 <__PRETTY_FUNCTION__.20324>
> > "varFree") at assert.c:92
> > #3  0x00007ffff5dadc82 in __GI___assert_fail (assertion=0x17ca38c
> > "(*var)->probindex == -1", file=0x17c8e60 "src/scip/var.c", line=2663,
> > function=0x17d2e68 <__PRETTY_FUNCTION__.20324> "varFree") at assert.c:101
> > #4  0x0000000000d5a555 in varFree (var=0x7fffffffd0a0, blkmem=0x27d5f70,
> > set=0x27d8170, eventqueue=0x0, lp=0x0) at src/scip/var.c:2663
> > #5  0x0000000000d5b660 in SCIPvarRelease (var=0x7fffffffd0a0,
> > blkmem=0x27d5f70, set=0x27d8170, eventqueue=0x0, lp=0x0) at
> > src/scip/var.c:2782
> > #6  0x0000000000c07d83 in SCIPreleaseVar (scip=0x27d2f70,
> > var=0x7fffffffd0a0) at src/scip/scip.c:18398
> > #7  0x000000000048bcf3 in hashtablefreeArrow (scip=0x27d2f70,
> > psd=0x2a057d0, releasevars=1) at src/utils.c:212
> > #8  0x000000000045a7e9 in PS_deallocateParentSetData (scip=0x27d2f70,
> > psd=0x29fa9d0, releasevars=1) at src/parent_set_data.c:94
> > #9  0x000000000046508c in probdelorigBN (scip=0x27d2f70,
> > probdata=0x29fbb88) at src/probdata_bn.c:96
> > #10 0x0000000000b48c07 in SCIPprobFree (prob=0x27d2fa8,
> > messagehdlr=0x27d3090, blkmem=0x27d5f70, set=0x27d8170, stat=0x29faa50,
> > eventqueue=0x0, lp=0x0) at src/scip/prob.c:448
> > #11 0x0000000000bd1312 in SCIPfreeProb (scip=0x27d2f70) at
> > src/scip/scip.c:10409
> > #12 0x00000000004aa060 in main (argc=2, argv=0x7fffffffd8e8) at
> > src/gobnilp.c:516
> >
> > Any ideas out there and what is going on, and how to fix it?
> >
> > James
> >
> > --
> > James Cussens
> > Dept of Computer Science &
> > York Centre for Complex Systems Analysis
> > Room 326, The Hub, Deramore Lane            Tel    +44 (0)1904 325371
> > University of York                                        Fax  +44
> > (0)1904 500159
> > York YO10 5GE, UK
> > http://www.cs.york.ac.uk/~jc <http://www.cs.york.ac.uk/%7Ejc>
> > http://www.york.ac.uk/docs/disclaimer/email.htm
> >
> >
> > _______________________________________________
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> >
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-- 
James Cussens
Dept of Computer Science &
York Centre for Complex Systems Analysis
Room 326, The Hub, Deramore Lane            Tel    +44 (0)1904 325371
University of York                                        Fax  +44 (0)1904
500159
York YO10 5GE, UK                               http://www.cs.york.ac.uk/~jc
http://www.york.ac.uk/docs/disclaimer/email.htm
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