Re: make printing to file faster

From:
Lord Zoltar <lord.zoltar@gmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 6 May 2008 13:35:27 -0700 (PDT)
Message-ID:
<98bc39f8-749b-4b35-aae1-dd4de1b6ed41@b1g2000hsg.googlegroups.com>
On May 6, 3:06 pm, Vlad Ciubotariu <vcciu...@uwaterloo.ca> wrote:

I'm printing a list of arrays of int to a file. The performance of the
code below is pretty bad. Any suggestions on how to improve it?

thanks
vlad

                try {
                        PrintStream out = new Pr=

intStream(inputFile);

                        out.println("p cnf " + num=

Vars + " " + numClauses);

                        for (Clause c : clauses) {=

                                for (int l=

iteral : c.getLiterals()) {

                                    =

    out.print(literal);

                                    =

    out.print(" ");

                                }
                                out.printl=

n(0);

                        }
                        for (Clause c : constraint=

s) {

                                for (int l=

iteral : c.getLiterals()) {

                                    =

    out.print(literal);

                                    =

    out.print(" ");

                                }
                                out.printl=

n(0);

                        }
                        out.close();
                } catch (IOException e) {
                        throw new RuntimeException=

("Could not write clauses to file: " + e.getMessage());

                }

And this is the performance for large repetitions:

  1.6% - 16,459 ms - 1 inv. ca.uwaterloo.watform.ckt.sat.SatSolver.solve=

  0.8% - 8,289 ms - 664,818 inv. java.io.PrintStream.print(int)
  0.4% - 4,091 ms - 249,391 inv. java.io.PrintStream.println(int)
  0.2% - 2,275 ms - 664,818 inv. java.io.PrintStream.print(java.lang.Str=

ing)

Instead of constantly doing out.print inside each loop, what if you
write to a StringBuffer and then write that to a file at the end?
Other way to improve performance would probably be to remove any
repeated or unnecessary clauses or constraints.

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