[AMPL 1821] "can't open at3916.nl" -- swap file error?

[Jacob JKW]

When running numerous solves in succession on Windows I frequently
receive an error of the form "can't open at3916.nl", which then kills
my ampl process.

I can only assume that this is some swap file issue. Is there anyway
around this? Perhaps a way to specify that AMPL automatically retry?


Thanks in advance,
J.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "AMPL Modeling Language" group.
To post to this group, send email to ampl@...
To unsubscribe from this group, send email to ampl-unsubscribe@...
For more options, visit this group at http://groups.google.com/group/ampl?hl=en
-~----------~----~----~----~------~----~------~--~---

[Robert Fourer-2]

The sequece of steps in solving a problem is as follows:

   -- you give the "solve" command to AMPL
   -- AMPL writes the optimization problem to file "at3916.nl"
   -- AMPL invokes the solver with "at3916" as an argument
   -- the solver reads the file "at3916.nl"

Thus "can't open at3916.nl" is an indication that the file "at3916.nl" was
not successfully written by AMPL, and yet the solver was subsequently
invoked by AMPL.  This might happen, for example, if space runs out on the
disk drive where the file is being written.

The first step in tracking down the specific problem in your case would be
to look for other error messages that appear just prior to "can't open
at3916.nl" -- they might indicate what the problem is.  Also you might get
more useful messages if, before "solve;", you give the command "write
btest;" which explicitly directs AMPL to write the file "test.nl" before
asking the solver to read it.

Bob Fourer
4er@...

> -----Original Message-----
> From: ampl@... [mailto:ampl@...] On Behalf Of
> Jacob JKW
> Sent: Wednesday, June 11, 2008 6:47 AM
> To: AMPL Modeling Language
> Subject: [AMPL 1821] "can't open at3916.nl" -- swap file error?
>
> When running numerous solves in succession on Windows I frequently
> receive an error of the form "can't open at3916.nl", which then kills
> my ampl process.
>
> I can only assume that this is some swap file issue. Is there anyway
> around this? Perhaps a way to specify that AMPL automatically retry?
>
> Thanks in advance,
> J.

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "AMPL Modeling Language" group.
To post to this group, send email to ampl@...
To unsubscribe from this group, send email to ampl-unsubscribe@...
For more options, visit this group at http://groups.google.com/group/ampl?hl=en
-~----------~----~----~----~------~----~------~--~---

[Haluk Yapicioglu]

Dear AMPL users,

 

my question is not directly realted with AMPL, I am using Java to access CPLEX optimizers. Recently, we switched from CPLEX 9.1 to 11.0, and the fprograms working just fine with CPLEX 9.1 started to give this error:

 

java.lang.UnsatisfiedLinkError: no cplex110 in java.library.path

java.library.path must point to the directory containing the CPLEX shared library

try invoking java with java -Djava.library.path=...

Exception in thread "main" java.lang.UnsatisfiedLinkError: CPXopenCPLEX

at ilog.cplex.Cplex.CPXopenCPLEX(Native Method)

at ilog.cplex.CplexI.init(CplexI.java:5094)

at ilog.cplex.CplexI.<init>(CplexI.java:512)

at ilog.cplex.IloCplex.<init>(IloCplex.java:8403)

at main.main(main.java:17)

any idea what may cause this?

Haluk

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "AMPL Modeling Language" group.
To post to this group, send email to ampl@...
To unsubscribe from this group, send email to ampl-unsubscribe@...
For more options, visit this group at http://groups.google.com/group/ampl?hl=en
-~----------~----~----~----~------~----~------~--~---

[Jacob JKW]

> The first step in tracking down the specific problem in your case would be
> to look for other error messages that appear just prior to "can't open
> at3916.nl" -- they might indicate what the problem is.  Also you might get
> more useful messages if, before "solve;", you give the command "write
> btest;" which explicitly directs AMPL to write the file "test.nl" before
> asking the solver to read it.
No there were no other error messages given.

I'm sure it had something to do with peculiar timing issues related to
the opening and closing of file handles under Windows.

The workaround I'm using (based on your advice) is just a simple:

        let write_file_name := ('bnlsol\test_SOME_ID_' & time());
        write(write_file_name);
        solve;
        close(write_file_name);

Haven't had the problem since.

Thank you once again. :)
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "AMPL Modeling Language" group.
To post to this group, send email to ampl@...
To unsubscribe from this group, send email to ampl-unsubscribe@...
For more options, visit this group at http://groups.google.com/group/ampl?hl=en
-~----------~----~----~----~------~----~------~--~---