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POLonger execution through Java shell than console?
 

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  1. POLonger execution through Java shell than console?
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    <p>I have a script in Python which do some computations. When I run this script in console it takes about 7 minutes to complete but when I run it thought Java shell it takes three times longer. I use following code to execute the script in Java:</p> <pre><code>this.p = Runtime.getRuntime().exec("script.py --batch", envp); this.input = new BufferedReader(new InputStreamReader(p.getInputStream())); this.output = new BufferedWriter(new OutputStreamWriter(p.getOutputStream())); this.error = new BufferedReader(new InputStreamReader(p.getErrorStream())); </code></pre> <p>Do you have any suggestion why the Python script runs three time longer in Java than in a console?</p> <p><strong>update (29.12.2010)</strong></p> <p>The computation goes as follow:</p> <ol> <li>Java sends data to the Python.</li> <li>Python reads the data.</li> <li>Python generates a decision tree --- this is a long operation.</li> <li>Python sends a confirmation that the tree is ready.</li> <li>Java receives the confirmation.</li> </ol> <p>Later there is a series of communications between Java and Python but it takes only several second.</p> <p><strong>update (29.12.2010)</strong></p> <p>Thank you for all your comments and suggestions. It took one working day to find out that my assumption was wrong. The code I used had 'a bug' and in fact different computation were performed in console and in shell. When I fixed it the computation time was the same. </p> <p><em>Summary</em>: The computation time of a script run in console and in Java shell is almost the same. The additional time for initialize Java VM and IO communication is insignificant. </p>
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    1. COIs there a lot of IO? Or is it a CPU-bound process?
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    2. COIt is CPU-bound process. The script receives data only at the beginning but this is done quickly. After that the script creates a decision tree what is very time-consuming.
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    3. COWhat are you doing with `input` and `error`? Throwing it away or keeping it in memory? And how much output does you program generate to these streams?
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