Process hangs in waitFor()

Question

I am trying to run mysql to execute some files from java. The input is read from a file and should be piped into the mysql process, everthing seems ok but the line

int exitCode = proc.waitFor();

never returns.

private boolean runScript(String path, String cmd, File file) throws IOException, InterruptedException {
        Runtime rt = Runtime.getRuntime();
        Process proc = rt.exec( path + File.separatorChar + cmd );
        OutputStream procOS = proc.getOutputStream();
        InputStream procES = proc.getErrorStream();
        InputStream procIS = proc.getInputStream();
        OutputStreamWriter procStdIn = new OutputStreamWriter( procOS );

        FileInputStream fis = new FileInputStream( file );
        BufferedReader reader = new BufferedReader( new InputStreamReader( fis ) );
        String send;

        while ( ( send = reader.readLine() ) != null ) {
            procStdIn.write( send );
            System.out.println( send );
            copyStream( procES, System.err );
            copyStream( procIS, System.out );
        }
        procStdIn.write( "\r\nexit\r\n" );
        int exitCode = proc.waitFor();
        return exitCode == 0;
    }

    private void copyStream(InputStream is, PrintStream err) throws IOException {
        byte b[] = new byte[ 1024 ];
        int length;
        while ( is.available() > 0 && ( length = is.read( b ) ) > 0 ) {
            err.write( b, 0, length );
        }

}

Do you see that the child process has exited? Perhaps the `copyStream` needs to be done one last time after writing `exit` to it? — Miserable Variable, Sep 12 '11 at 12:53

score 3 · Accepted Answer · edited May 23 '17 at 12:16

3

I suspect you're blocking reading stdout and stderr. See this answer for more details.

edited May 23 '17 at 12:16

Community

1
1

answered Sep 12 '11 at 12:53

Brian Agnew

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sorry the copyStream method does not block due to the call of avaliable(). – stacker Sep 12 '11 at 14:53
1

Thanks the problem was the missing flush() on mysqls input stream. – stacker Sep 12 '11 at 15:00

score 0 · Answer 2 · answered Oct 01 '15 at 20:21

0

Add:

procStdIn.flush();

after:

procStdIn.write( "\r\nexit\r\n" );

answered Oct 01 '15 at 20:21

Nicolas

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Process hangs in waitFor()

2 Answers2

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