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chfloodchflood
committedMay 7, 2019
Prototype for Java Checkpoint Restore
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‎CheckpointRestore.cpp

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#include "CheckpointRestore.hpp"
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#include <criu.h>
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <jni.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/un.h>
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#include <sys/wait.h>
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#include <unistd.h>
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JNIEXPORT void JNICALL Java_CheckpointRestore_CheckTheWorldNative(JNIEnv *env, jobject obj) {
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int init_result = criu_init_opts();
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if (init_result < 0) {
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perror("Can't init opts");
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}
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int result = criu_check();
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if (result == 0) {
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printf("Criu Check success\n");
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} else {
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printf("Criu Check failed with error: %d: %s\n", result, strerror(result));
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}
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return;
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}
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JNIEXPORT void JNICALL Java_CheckpointRestore_SaveTheWorldNative (JNIEnv * env, jobject jobj, jstring jstr) {
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const char * path = env->GetStringUTFChars(jstr, NULL);
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struct stat st = {0};
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if (stat(path, &st) == -1) {
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mkdir(path, 0700);
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}
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int fd = open(path, O_DIRECTORY);
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printf("\npath = %s\n",path);
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if (fd < 0) {
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perror("Can't open images dir");
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}
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int init_result = criu_init_opts();
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if (init_result < 0) {
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perror("Can't init opts");
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}
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criu_set_images_dir_fd(fd);
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criu_set_shell_job(true);
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criu_set_log_level(4);
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criu_set_log_file((char *) "save.log");
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criu_set_leave_running(true);
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criu_set_ext_unix_sk(true);
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int ret = criu_dump();
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if (ret == 0) {
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printf("Successful dump\n");
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} else {
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printf("Error from dump %d\n", ret);
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perror("Dump Error");
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}
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}
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/*
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* Class: CheckpointRestore
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* Method: RestoreTheWorld
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* Signature: ()V
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*/
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JNIEXPORT void JNICALL Java_CheckpointRestore_RestoreTheWorldNative
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(JNIEnv * env, jobject jobj, jstring jstr) {
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const char * path = env->GetStringUTFChars(jstr, NULL);
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printf("\nRestore The World Path = %s\n",path);
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int fd = open(path, O_DIRECTORY);
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if (fd < 0) {
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perror("Can't open images dir");
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}
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int init_result = criu_init_opts();
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if (init_result < 0) {
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perror("Can't init opts");
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}
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printf("RestoreTheWorld: file = %s fd = %d\n", path, fd);
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criu_set_shell_job(true);
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criu_set_images_dir_fd(fd);
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criu_set_log_file((char *) "chfrestore.log");
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criu_set_log_level(4);
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int pid = criu_restore_child();
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printf("\npid = %d\n", pid);
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if (pid < 0) {
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perror("Criu Restore Bad Pid \n");
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} else {
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int status = 0;
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int result = waitpid(pid, &status, 0);
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if (result < 0) {
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printf("pid = %d status = %d result = %d\n", pid, status, result);
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perror("Can't wait rchild");
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}
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}
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}
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/*
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* Class: CheckpointRestore
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* Method: MigrateTheWorld
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* Signature: ()V
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*/
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JNIEXPORT void JNICALL Java_CheckpointRestore_MigrateTheWorld
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(JNIEnv *, jobject);
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/*
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* Class: CheckpointRestore
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* Method: SaveTheWorldIncremental
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* Signature: ()V
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*/
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JNIEXPORT void JNICALL Java_CheckpointRestore_SaveTheWorldIncremental
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(JNIEnv *, jobject);
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‎CheckpointRestore.java

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import java.util.Map;
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public class CheckpointRestore {
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public static void CleanupTheWorld() {
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System.gc();
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System.gc();
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}
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private native void CheckTheWorldNative();
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private native void SaveTheWorldNative(String dir);
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private native void RestoreTheWorldNative(String dir);
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public static native void MigrateTheWorld();
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public static native void SaveTheWorldIncremental();
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public static void CheckTheWorld() {
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CheckpointRestore cr = new CheckpointRestore();
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cr.CheckTheWorldNative();
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}
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public static void SaveTheWorld(String dir) {
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CheckpointRestore cr = new CheckpointRestore();
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cr.SaveTheWorldNative(dir);
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}
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public static void RestoreTheWorld(String dir) {
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System.out.println("RestoreTheWorld java call");
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CheckpointRestore cr = new CheckpointRestore();
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cr.RestoreTheWorldNative(dir);
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}
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static {
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System.out.println("Library path = " + System.getProperty("java.library.path"));
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System.out.println("About to load Checkpoint Restore library " + System.mapLibraryName("CheckpointRestore"));
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System.out.println("About to load criu library " + System.mapLibraryName("criu"));
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System.out.println("Before call to load CheckpointRestore");
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System.loadLibrary("CheckpointRestore");
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System.out.println("After call to load CheckpointRestore");
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System.loadLibrary("criu");
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System.out.println("After call to load criu");
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}
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}

‎ReadMe

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This is demo code to show how to use CRIU (Checkpoint Restore In Userspace) from Java.
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It's very much a prototype. There are many caveats in this file. Please try it and let me know how it goes.
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chf@redhat.com
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Make sure criu is running from the directory that has the socket file.
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[cflood@cflood FromInsideJava]$ sudo /home/cflood/criu/criu-latest/criu/criu service
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Warn (criu/cr-service.c:1160): Binding to local dir address!
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Make sure kernel is compiled with CR turned on
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sudo grep CHECKPOINT /boot/config-*
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javac CheckpointRestore.java
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javah CheckpointRestore
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mv CheckpointRestore.h CheckpointRestore.hpp
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Make sure criu is installed and libcriu is on your library path. I set mine via
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export LOAD_LIBRARY_PATH=/usr/lib64:./
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There is probably a better way
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Build the criu library.
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gcc -shared -fPIC -I/usr/lib/jvm/java-openjdk/include -I/usr/lib/jvm/java-openjdk/include/linux -I/usr/lib64/ -I/usr/include/criu -lcriu -o libCheckpointRestore.so CheckpointRestore.cpp
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There is currently a problem with a socket file which is causing tests to fail. The short term fix is to delete this file.
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I did rm -rf rm -f /var/lib/sss/pipes/nss
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I'm working on addressing this problem.
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You can now checkpoint java code:
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sudo setsid java -XX:+UseSerialGC -XX:-UsePerfData -Djava.library.path=$LOAD_LIBRARY_PATH TestRandom 1000000 1000
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and restore:
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sudo bash
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cd /home/chf/SavedWorlds/run<x>
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criu restore --shell-job

‎TestRandom.java

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public class TestRandom {
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public static void main(String[] args) {
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if (args.length != 2) System.out.println("Usage: please provide upper bound and sample size");
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int upperBound = Integer.parseInt(args[0]);
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long sampleSize = Long.parseLong(args[1]);
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long testarray[] = new long[upperBound];
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for (long i = 0; i < sampleSize; i++) {
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Double r = Math.random() * upperBound;
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int v = (int) Math.floor(r);
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testarray[v] += 1;
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}
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System.out.println("Before any goodness");
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CheckpointRestore.CheckTheWorld();
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long end = System.currentTimeMillis();
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System.out.println("Saving the world in directory /home/chf/SavedWorlds/run" + end);
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CheckpointRestore.SaveTheWorld("/home/chf/SavedWorlds/run" + end);
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long max = 0; long min = upperBound; long average = 0;
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for (int i = 0; i < upperBound; i++) {
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long s = testarray[i];
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if (s > max) { max = s;}
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if (s < min) { min = s;}
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average = average + s;
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}
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double median = average / upperBound;
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System.out.println("Testing random number generator with upper bound = " + upperBound + " and sample size " + sampleSize);
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System.out.println("Max bin size = " + max + " Min bin size = " + min + " median bin size = " + median);
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}
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}

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