/**
* Builds a list of arguments to run java.
*
* <p>This method finds the java executable to use and appends JVM-specific options for running a
* class with Spark in the classpath. It also loads options from the "java-opts" file in the
* configuration directory being used.
*
* <p>Callers should still add at least the class to run, as well as any arguments to pass to the
* class.
*/
List<String> buildJavaCommand(String extraClassPath) throws IOException {
List<String> cmd = new ArrayList<String>();
String envJavaHome;
if (javaHome != null) {
cmd.add(join(File.separator, javaHome, "bin", "java"));
} else if ((envJavaHome = System.getenv("JAVA_HOME")) != null) {
cmd.add(join(File.separator, envJavaHome, "bin", "java"));
} else {
cmd.add(join(File.separator, System.getProperty("java.home"), "bin", "java"));
}
// Load extra JAVA_OPTS from conf/java-opts, if it exists.
File javaOpts = new File(join(File.separator, getConfDir(), "java-opts"));
if (javaOpts.isFile()) {
BufferedReader br =
new BufferedReader(new InputStreamReader(new FileInputStream(javaOpts), "UTF-8"));
try {
String line;
while ((line = br.readLine()) != null) {
addOptionString(cmd, line);
}
} finally {
br.close();
}
}
cmd.add("-cp");
cmd.add(join(File.pathSeparator, buildClassPath(extraClassPath)));
return cmd;
}
/**
* Adds the default perm gen size option for Spark if the VM requires it and the user hasn't set
* it.
*/
void addPermGenSizeOpt(List<String> cmd) {
// Don't set MaxPermSize for IBM Java, or Oracle Java 8 and later.
if (getJavaVendor() == JavaVendor.IBM) {
return;
}
String[] version = System.getProperty("java.version").split("\\.");
if (Integer.parseInt(version[0]) > 1 || Integer.parseInt(version[1]) > 7) {
return;
}
for (String arg : cmd) {
if (arg.startsWith("-XX:MaxPermSize=")) {
return;
}
}
cmd.add("-XX:MaxPermSize=128m");
}