Forum Discussion
Parallel processing in Xpress
Hi everyone!
I am trying to run submodels in parallel in xpress and I am experiencing a few issues.
1 - Can I define a constant value of a submodel with a command line: for instance: run(myMod,t=2)?
-------------------
2 - I am trying to share memory from a subproblem "s" as follows:
initializations to "bin:shmem:output" + s
output
end-initializations.
But when I try to read this memory from my master problem as
initializations from "bin:shmem:output" + s
output
end-initializations.
I get an error mesage: Mosel: E-22: I cannot open file `shmem:output1' for reading (file not found).
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3 - If I try to share results with txt files, it works for most of the time but from time to time I also get an error mesage E-22 for the text file. I know that this is probably an issue of more than one parallel procedure trying to assess the same file, but I though my code could handle this:
initializations to 'submodel_input.txt'
t s
end-initilizations
forall s in submodelsSet do
run(submodel)****
end-do
forall s in submodelsSet do
wait
end-do
forall s in submodelsSet do
initializations from 'submodel_output' + s + '.txt'
output
end-initializations
end-do
****Inside of each submodel I write the output as follows
initializations to 'submodel_output' + s + '.txt'
output
end-initializations
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Could someone please help me with these issues?
All the best
Arthur.
2 Replies
1 - You can set runtime parameters for submodels directly with the "run" command of mmjobs:
run(myMod, "t=2,mystring='some text'")
or via "setmodpar":
declarations
params:text
end-declarations
setmodpar(params, "t", 2)
setmodpar(params, "mystring", "some text")
run(myMod, params)
2/3 - Does your master model "wait" for submodel termination - or for some other event message sent by the submodel to signal that data are available for reading?
Please take a look at the example FICO Xpress Examples Repository: Working with multiple models: submodels, coordination, communication, and parallelizati… (http://examples.xpress.fico.com/example.pl?id=mosel_solv_9_12) documented in Section 2.7 "Communication of data between different models" of the whitepaper "Multiple models and parallel solving with Mosel" (contained in the "docs" subdirectory of the standard Xpress distribution) or section 17.2.3 "Exchanging data between models" of the Mosel User Guide ( FICO Xpress Examples Repository: Calculating prime numbers (http://examples.xpress.fico.com/example.pl?id=mosel_xprd_prime_0_m)).
Thank you very much Susanne! I have managed to get it to work.
