ReadMe

This is demo code to show how to use CRIU (Checkpoint Restore In Userspace) from Java.

It's very much a prototype.  There are many caveats in this file.  Please try it and let me know how it goes.

1) Make sure CRIU is enabled in your kernel 
sudo grep CHECKPOINT /boot/config-*

2) Make sure you are running criu version 3.11 or higher

3) Make sure criu service is running (socket create) in the same directory as your socket file.
sudo criu service&
Warn  (criu/cr-service.c:1160): Binding to local dir address!

4) One last check
sudo criu check

5) Compile the java file
javac CheckpointRestore.java

6) Generate the .h file
javah CheckpointRestore

7) Make it into a .hpp file
mv CheckpointRestore.h CheckpointRestore.hpp

8) Make sure criu is installed and libcriu is on your library path.  I set mine via
export LOAD_LIBRARY_PATH=/usr/lib64:./
There is probably a better way

9) Build the criu library.
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

10) You can now checkpoint java code:
sudo setsid java -XX:+UseSerialGC -XX:-UsePerfData -Djava.library.path=$LOAD_LIBRARY_PATH TestRandom 1000000 1000

11) The command to restore will be printed during checkpointing.  Mine was:

sudo java -XX:+UseSerialGC -XX:-UsePerfData -Djava.library.path=$LOAD_LIBRARY_PATH  TestRandomRestore <saved world directory>


Known Issues:

There is currently a problem with a socket file which is causing tests to fail.  The short term fix is to delete this file.
I did rm -rf rm -f /var/lib/sss/pipes/nss
I'm working on addressing this problem.

Saving Performance Data causes the generation of open files which can't be closed.

ParallelGC causes an issue.