Example usage for org.apache.hadoop.mapreduce.util ProcessTree isSetsidAvailable

Introduction

In this page you can find the example usage for org.apache.hadoop.mapreduce.util ProcessTree isSetsidAvailable.

Prototype

boolean isSetsidAvailable

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Usage

From source file:it.crs4.pydoop.mapreduce.pipes.TaskLog.java

License:Apache License

/**
 * Construct the command line for running the task JVM
 * @param setup The setup commands for the execed process.
 * @param cmd The command and the arguments that should be run
 * @param stdoutFilename The filename that stdout should be saved to
 * @param stderrFilename The filename that stderr should be saved to
 * @param tailLength The length of the tail to be saved.
 * @return the command line as a String//ww w . j  av  a2s .  c  om
 * @throws IOException
 */
static String buildCommandLine(List<String> setup, List<String> cmd, File stdoutFilename, File stderrFilename,
        long tailLength, boolean useSetsid) throws IOException {

    String stdout = FileUtil.makeShellPath(stdoutFilename);
    String stderr = FileUtil.makeShellPath(stderrFilename);
    StringBuffer mergedCmd = new StringBuffer();

    // Export the pid of taskJvm to env variable JVM_PID.
    // Currently pid is not used on Windows
    if (!Shell.WINDOWS) {
        mergedCmd.append(" export JVM_PID=`echo $$` ; ");
    }

    if (setup != null && setup.size() > 0) {
        mergedCmd.append(addCommand(setup, false));
        mergedCmd.append(";");
    }
    if (tailLength > 0) {
        mergedCmd.append("(");
    } else if (ProcessTree.isSetsidAvailable && useSetsid && !Shell.WINDOWS) {
        mergedCmd.append("exec setsid ");
    } else {
        mergedCmd.append("exec ");
    }
    mergedCmd.append(addCommand(cmd, true));
    mergedCmd.append(" < /dev/null ");
    if (tailLength > 0) {
        mergedCmd.append(" | ");
        mergedCmd.append(tailCommand);
        mergedCmd.append(" -c ");
        mergedCmd.append(tailLength);
        mergedCmd.append(" >> ");
        mergedCmd.append(stdout);
        mergedCmd.append(" ; exit $PIPESTATUS ) 2>&1 | ");
        mergedCmd.append(tailCommand);
        mergedCmd.append(" -c ");
        mergedCmd.append(tailLength);
        mergedCmd.append(" >> ");
        mergedCmd.append(stderr);
        mergedCmd.append(" ; exit $PIPESTATUS");
    } else {
        mergedCmd.append(" 1>> ");
        mergedCmd.append(stdout);
        mergedCmd.append(" 2>> ");
        mergedCmd.append(stderr);
    }
    return mergedCmd.toString();
}

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