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<font size="-1"><font size="-1">J</font>ohn,<br>
<br>
<font size="-1">I've not <font size="-1">realiz<font size="-1">ed
th<font size="-1">at this mail was including my answer. And<font
size="-1">, <font size="-1">i did not see yours...<br>
Thanks for your fix.<br>
<font size="-1"><font size="-1">That works fine!<br>
<br>
<font size="-1">Regards,<br>
<br>
<font size="-1">Yves</font><br>
</font></font></font><br>
<br>
</font></font></font></font></font></font></font>
<div class="moz-cite-prefix">On 12/20/2013 06:00 PM,
<a class="moz-txt-link-abbreviated" href="mailto:cbc-request@list.coin-or.org">cbc-request@list.coin-or.org</a> wrote:<br>
</div>
<blockquote
cite="mid:mailman.3.1387558801.25424.cbc@list.coin-or.org"
type="cite">
<pre wrap="">Send Cbc mailing list submissions to
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When replying, please edit your Subject line so it is more specific
than "Re: Contents of Cbc digest..."
Today's Topics:
1. Re: Threadsafe usage of Cbc (Pietro Belotti)
2. Re: Cbc Digest, Vol 78, Issue 6 (Yves Touchard)
3. Re: Constraints order (John Forrest)
----------------------------------------------------------------------
Message: 1
Date: Thu, 19 Dec 2013 18:59:12 +0000
From: Pietro Belotti <a class="moz-txt-link-rfc2396E" href="mailto:petr.7b6@gmail.com"><petr.7b6@gmail.com></a>
To: Cornelius Riemenschneider <a class="moz-txt-link-rfc2396E" href="mailto:cri@itscope.de"><cri@itscope.de></a>
Cc: <a class="moz-txt-link-rfc2396E" href="mailto:cbc@list.coin-or.org">"cbc@list.coin-or.org"</a> <a class="moz-txt-link-rfc2396E" href="mailto:cbc@list.coin-or.org"><cbc@list.coin-or.org></a>
Subject: Re: [Cbc] Threadsafe usage of Cbc
Message-ID:
<a class="moz-txt-link-rfc2396E" href="mailto:CAA1=4dgC3d8XKuxRTLLOTcGEOOa3dE21ZW_PkVUU0rPLoUtnMQ@mail.gmail.com"><CAA1=4dgC3d8XKuxRTLLOTcGEOOa3dE21ZW_PkVUU0rPLoUtnMQ@mail.gmail.com></a>
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A bit more information about Couenne: there is some code in Couenne to
make it possible, in the future, to use threads (for instance, it can
be configured with --enable-cbc-parallel), but as far as I understand
Couenne is still sequential. There are a few major changes to be made
for this to happen. I was able to code a Branch-and-bound for problems
with a specific class of nonlinear constraints and it does run in
parallel (under Linux only), but that's that.
Pietro
On Thu, Dec 19, 2013 at 3:44 PM, Cornelius Riemenschneider
<a class="moz-txt-link-rfc2396E" href="mailto:cri@itscope.de"><cri@itscope.de></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hello,
thank you very much for your work!
As I?ll be away for the holidays, I?ll try your patch in the new year and
will report back.
Can you elaborate on the cut generator problem? Is it user-specified which
one is used, or is this a choice done by the algorithm?
And can you point me at the source code for them, so that I can check them
for thread safety in case we actually use them?
Regards,
Cornelius Riemenschneider
--
ITscope GmbH
Ludwig-Erhard-Allee 20
76131 Karlsruhe
Email: <a class="moz-txt-link-abbreviated" href="mailto:cornelius.riemenschneider@itscope.de">cornelius.riemenschneider@itscope.de</a>
<a class="moz-txt-link-freetext" href="https://www.itscope.com">https://www.itscope.com</a>
Handelsregister: AG Mannheim, HRB 232782
Sitz der Gesellschaft: Karlsruhe
Gesch?ftsf?hrer: Alexander M?nkel, Benjamin Mund, Stefan Reger
Von: <a class="moz-txt-link-abbreviated" href="mailto:john.forrest@fastercoin.com">john.forrest@fastercoin.com</a> [<a class="moz-txt-link-freetext" href="mailto:cbc-bounces@list.coin-or.org">mailto:cbc-bounces@list.coin-or.org</a>] Im
Auftrag von John Forrest
Gesendet: Mittwoch, 18. Dezember 2013 14:23
An: <a class="moz-txt-link-abbreviated" href="mailto:cbc@list.coin-or.org">cbc@list.coin-or.org</a>
Betreff: Re: [Cbc] Threadsafe usage of Cbc
Cornelius,
I have made some changes, which I hope will be enough for you. I have done
the minimum amount of work.
I don't think they can hurt anyone but as Ted Ralphs is preparing a new
release, I will delay updating Cbc/stable/CbcSolver.?pp for a day or two.
If anyone wants to test the code I attach CbcSolver.?pp.
You need to compile with -DCBC_THREAD_SAFE. The main thing this does is
that Cbc only reads argv/argc type parameters in a crude threadsafe way.
You also need to use alternative versions of CbcMain0/1.
parallel.cpp has been added to Cbc/examples which is a simple example.
Please tell me if there are any problems. Some lesser used Cgl cut
generators may not be threadsafe, but I think the commonly used ones are.
John Forrest
On 17/12/13 15:11, Cornelius Riemenschneider wrote:
Hello,
we use CBC via googles or-tools from java in our application.
Compared to scientific problems, our problems are small and solved by Cbc in
<1s (which is great!).
As we process requests from users concurrently, we?d also like to call Cbc
concurrently.
Currently, this is impossible, because Cbc uses the static parameters array
in CbcMain0 and CbcMain1 and thus crashes or reads incorrect parameters.
One backtrace, for example is:
#2 0x00007fb3435bf52b in __libc_message (do_abort=<optimized out>,
fmt=<optimized out>) at ../sysdeps/unix/sysv/linux/libc_fatal.c:189
#3 0x00007fb3435c8d76 in malloc_printerr (action=3, str=0x7fb3436a1248
"double free or corruption (!prev)", ptr=<optimized out>) at malloc.c:6283
#4 0x00007fb3435cdaac in *__GI___libc_free (mem=<optimized out>) at
malloc.c:3738
#5 0x00007fb342733f06 in std::string::assign(std::string const&) () from
/usr/lib/x86_64-linux-gnu/libstdc++.so.6
#6 0x00007fb2d652cb7b in establishParams(int&, CbcOrClpParam*) () from
libjnilinearsolver.so
#7 0x00007fb2d64edc3b in CbcMain0(CbcModel&) () from libjnilinearsolver.so
#8 0x00007fb2d6511bec in callCbc(char const*, CbcModel&) () from
libjnilinearsolver.so
#9 0x00007fb2d64e3fce in
operations_research::CBCInterface::Solve(operations_research::MPSolverParameters
const&) () from libjnilinearsolver.so
#10 0x00007fb2d64cfe45 in
operations_research::MPSolver::Solve(operations_research::MPSolverParameters
const&) () from libjnilinearsolver.so
#11 0x00007fb2d64cff3b in operations_research::MPSolver::Solve() () from
libjnilinearsolver.so
#12 0x00007fb2d64c91cf in
Java_com_google_ortools_linearsolver_mainJNI_MPSolver_1solve_1_1SWIG_10 ()
from libjnilinearsolver.so
# from here on it?s just the JVM
As I don?t know the code and it?s hard to read, I can?t really fix the
problem by myself,
but wouldn?t it be better to move parameters inside CbcModel instead of
having a static array laying around?
Andi f that?s done (or another solution is found), do you know of any
thread-safety issues in cbc?
Keep in mind, we don?t want Cbc to solve our problem in multiple threads, we
just want to be able to solve different problems simultaneous.
Regards,
Cornelius Riemenschneider
--
ITscope GmbH
Ludwig-Erhard-Allee 20
76131 Karlsruhe
Email: <a class="moz-txt-link-abbreviated" href="mailto:cornelius.riemenschneider@itscope.de">cornelius.riemenschneider@itscope.de</a>
<a class="moz-txt-link-freetext" href="https://www.itscope.com">https://www.itscope.com</a>
Handelsregister: AG Mannheim, HRB 232782
Sitz der Gesellschaft: Karlsruhe
Gesch?ftsf?hrer: Alexander M?nkel, Benjamin Mund, Stefan Reger
_______________________________________________
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</pre>
</blockquote>
<pre wrap="">
------------------------------
Message: 2
Date: Fri, 20 Dec 2013 12:17:16 +0100
From: Yves Touchard <a class="moz-txt-link-rfc2396E" href="mailto:ytouchard@dxo.com"><ytouchard@dxo.com></a>
To: <a class="moz-txt-link-rfc2396E" href="mailto:cbc@list.coin-or.org"><cbc@list.coin-or.org></a>
Subject: Re: [Cbc] Cbc Digest, Vol 78, Issue 6
Message-ID: <a class="moz-txt-link-rfc2396E" href="mailto:52B4273C.7020805@dxo.com"><52B4273C.7020805@dxo.com></a>
Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
John,
Thank you very much for quick and efficient reply!
I have just a couple of questions.
First, do you know when this fix will be released?
Then, i am wondering if doing a constant propagation could help the solver.
My constraints file is generated by a piece of code which do not try to
optimize them.
For instance, the following sequence:
_C0: var_0 = 0
_C1: var_0 + var_2 >= var_3
could be replaced with:
_c0: var_2 >= var_3
Yves
</pre>
<blockquote type="cite">
<pre wrap="">----------------------------------------------------------------------
Message: 1
Date: Wed, 18 Dec 2013 19:48:38 +0000
From: John Forrest <a class="moz-txt-link-rfc2396E" href="mailto:john.forrest@fastercoin.com"><john.forrest@fastercoin.com></a>
To: <a class="moz-txt-link-abbreviated" href="mailto:cbc@list.coin-or.org">cbc@list.coin-or.org</a>
Subject: Re: [Cbc] Constraints order
Message-ID: <a class="moz-txt-link-rfc2396E" href="mailto:52B1FC16.6030301@fastercoin.com"><52B1FC16.6030301@fastercoin.com></a>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
Yves,
Error not where I thought it was. Small changes i.e. order or compiler
or anything made a subtle difference and a constraint was generated
x995 + x1018 + x1700 >= 1.0000001001
and the optimal solution had x995==0,x1018==1 and x1700==0 - but it was
within tolerances (just)
One of the cut generators then thought 0.0000001001 is greater than
primal tolerance of 1.0e-7 and created a bad cut.
I have modified code to be a bit more relaxed.
John Forrest
On 18/12/13 10:11, Yves Touchard wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Attached is a archive file (test.gz) containing an lp constraint file
(test.lp -> /tar xzf test.gz/)
Executing cbc (#2.8.0) on the test.lp file (/cbc test.lp/) provides
the following result
/Result - Problem proven infeasible//
//No feasible solution found
/If the two first constraints of the LP file (lines 1258/1259) are
swapped, the same command provides a different result:
/Result - Optimal solution found/
So, what's wrong with this constraints fle? Is there any specific
order to declare constraints?
Or is this a bug? And, if so, is there any workaround?
Thanks in advance for any help.
Regards,
Yves
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Message: 2
Date: Thu, 19 Dec 2013 16:44:40 +0100
From: Cornelius Riemenschneider <a class="moz-txt-link-rfc2396E" href="mailto:cri@itscope.de"><cri@itscope.de></a>
To: John Forrest <a class="moz-txt-link-rfc2396E" href="mailto:john.forrest@fastercoin.com"><john.forrest@fastercoin.com></a>,
"=?windows-1252?Q?cbc=40list.coin-or.org?=" <a class="moz-txt-link-rfc2396E" href="mailto:cbc@list.coin-or.org"><cbc@list.coin-or.org></a>
Subject: Re: [Cbc] Threadsafe usage of Cbc
Message-ID: <zarafa.52b31468.16aa.50cb38f25c72147c@noriswww>
Content-Type: text/plain; charset="iso-8859-1"
Hello,
thank you very much for your work!
As I?ll be away for the holidays, I?ll try your patch in the new year and will report back.
Can you elaborate on the cut generator problem? Is it user-specified which one is used, or is this a choice done by the algorithm?
And can you point me at the source code for them, so that I can check them for thread safety in case we actually use them?
?
Regards,
Cornelius Riemenschneider
--
ITscope GmbH
Ludwig-Erhard-Allee 20
76131 Karlsruhe
Email: <a class="moz-txt-link-abbreviated" href="mailto:cornelius.riemenschneider@itscope.de">cornelius.riemenschneider@itscope.de</a>
<a class="moz-txt-link-freetext" href="https://www.itscope.com">https://www.itscope.com</a>
Handelsregister: AG Mannheim, HRB 232782
Sitz der Gesellschaft: Karlsruhe
Gesch?ftsf?hrer: Alexander M?nkel, Benjamin Mund, Stefan Reger
?
Von: <a class="moz-txt-link-abbreviated" href="mailto:john.forrest@fastercoin.com">john.forrest@fastercoin.com</a> [<a class="moz-txt-link-freetext" href="mailto:cbc-bounces@list.coin-or.org">mailto:cbc-bounces@list.coin-or.org</a>] Im Auftrag von John Forrest
Gesendet: Mittwoch, 18. Dezember 2013 14:23
An: <a class="moz-txt-link-abbreviated" href="mailto:cbc@list.coin-or.org">cbc@list.coin-or.org</a>
Betreff: Re: [Cbc] Threadsafe usage of Cbc
?
Cornelius,
I have made some changes, which I hope will be enough for you.? I have done the minimum amount of work.
I don't think they can hurt anyone but as Ted Ralphs is preparing a new release, I will delay updating Cbc/stable/CbcSolver.?pp for a day or two.? If anyone wants to test the code I attach CbcSolver.?pp.
You need to compile with -DCBC_THREAD_SAFE.? The main thing this does is that Cbc only reads argv/argc type parameters in a crude threadsafe way.? You also need to use alternative versions of CbcMain0/1.
parallel.cpp has been added to Cbc/examples which is a simple example.
Please tell me if there are any problems.? Some lesser used Cgl cut generators may not be threadsafe, but I think the commonly used ones are.
John Forrest
On 17/12/13 15:11, Cornelius Riemenschneider wrote:
Hello,
we use CBC via googles or-tools from java in our application.
Compared to scientific problems, our problems are small and solved by Cbc in <1s (which is great!).
As we process requests from users concurrently, we?d also like to call Cbc concurrently.
Currently, this is impossible, because Cbc uses the static parameters array in CbcMain0 and CbcMain1 and thus crashes or reads incorrect parameters.
One backtrace, for example is:
?
#2 0x00007fb3435bf52b in __libc_message (do_abort=<optimized out>, fmt=<optimized out>) at ../sysdeps/unix/sysv/linux/libc_fatal.c:189
#3 0x00007fb3435c8d76 in malloc_printerr (action=3, str=0x7fb3436a1248 "double free or corruption (!prev)", ptr=<optimized out>) at malloc.c:6283
#4 0x00007fb3435cdaac in *__GI___libc_free (mem=<optimized out>) at malloc.c:3738
#5 0x00007fb342733f06 in std::string::assign(std::string const&) () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#6 0x00007fb2d652cb7b in establishParams(int&, CbcOrClpParam*) () from libjnilinearsolver.so
#7 0x00007fb2d64edc3b in CbcMain0(CbcModel&) () from libjnilinearsolver.so
#8 0x00007fb2d6511bec in callCbc(char const*, CbcModel&) () from libjnilinearsolver.so
#9 0x00007fb2d64e3fce in operations_research::CBCInterface::Solve(operations_research::MPSolverParameters const&) () from libjnilinearsolver.so
#10 0x00007fb2d64cfe45 in operations_research::MPSolver::Solve(operations_research::MPSolverParameters const&) () from libjnilinearsolver.so
#11 0x00007fb2d64cff3b in operations_research::MPSolver::Solve() () from libjnilinearsolver.so
#12 0x00007fb2d64c91cf in Java_com_google_ortools_linearsolver_mainJNI_MPSolver_1solve_1_1SWIG_10 () from libjnilinearsolver.so
# from here on it?s just the JVM
?
As I don?t know the code and it?s hard to read, I can?t really fix the problem by myself,
but wouldn?t it be better to move parameters inside CbcModel instead of having a static array laying around?
?
Andi f that?s done (or another solution is found), do you know of any thread-safety issues in cbc?
Keep in mind, we don?t want Cbc to solve our problem in multiple threads, we just want to be able to solve different problems simultaneous.
?
Regards,
Cornelius Riemenschneider
--
ITscope GmbH
Ludwig-Erhard-Allee 20
76131 Karlsruhe
Email: <a class="moz-txt-link-abbreviated" href="mailto:cornelius.riemenschneider@itscope.de">cornelius.riemenschneider@itscope.de</a>
<a class="moz-txt-link-freetext" href="https://www.itscope.com">https://www.itscope.com</a>
Handelsregister: AG Mannheim, HRB 232782
Sitz der Gesellschaft: Karlsruhe
Gesch?ftsf?hrer: Alexander M?nkel, Benjamin Mund, Stefan Reger
?
_______________________________________________
Cbc mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Cbc@list.coin-or.org">Cbc@list.coin-or.org</a>
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?
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End of Cbc Digest, Vol 78, Issue 6
**********************************
</pre>
</blockquote>
<pre wrap="">
------------------------------
Message: 3
Date: Fri, 20 Dec 2013 14:19:00 +0000
From: John Forrest <a class="moz-txt-link-rfc2396E" href="mailto:john.forrest@fastercoin.com"><john.forrest@fastercoin.com></a>
To: <a class="moz-txt-link-abbreviated" href="mailto:cbc@list.coin-or.org">cbc@list.coin-or.org</a>
Subject: Re: [Cbc] Constraints order
Message-ID: <a class="moz-txt-link-rfc2396E" href="mailto:52B451D4.1040102@fastercoin.com"><52B451D4.1040102@fastercoin.com></a>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
Yves,
Fix is in Cgl/stable/0.58 so if you are using svn just update. I don't
know when next release will be. As it only one file that has been
changed you could also just download it from
<a class="moz-txt-link-freetext" href="https://projects.coin-or.org/Cgl/browser/stable/0.58/Cgl/src/CglProbing/CglProbing.cpp">https://projects.coin-or.org/Cgl/browser/stable/0.58/Cgl/src/CglProbing/CglProbing.cpp</a>
The change you suggest would improve solution times by a tiny tiny
amount - but it normally is best to keep your code as simple (and
therefore bug free) as possible.
John Forrest
On 20/12/13 11:17, Yves Touchard wrote:
</pre>
<blockquote type="cite">
<pre wrap="">John,
Thank you very much for quick and efficient reply!
I have just a couple of questions.
First, do you know when this fix will be released?
Then, i am wondering if doing a constant propagation could help the
solver.
My constraints file is generated by a piece of code which do not try
to optimize them.
For instance, the following sequence:
_C0: var_0 = 0
_C1: var_0 + var_2 >= var_3
could be replaced with:
_c0: var_2 >= var_3
Yves
</pre>
</blockquote>
<pre wrap="">
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End of Cbc Digest, Vol 78, Issue 7
**********************************
</pre>
</blockquote>
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