multiOJ.sh will allow you to run many instances

put all your OJs home dir under same PATH
run  multiOJ.sh PATH with nohup & or screen -d -m
this should allow you to run dozens HUSTOJ instances in same VPS system 
the catch is the judge-response may slow down for each OJ
because they will be all in the same job queue

trunk/install/ multiOJ.sh

@@ -0,0 +1,13 @@
+function judge_round(){
+
+  for config in `sudo find -O2  "$1" -name judge.conf`
+  do
+     etc=`dirname "$config"`
+     home=`dirname "$etc"`
+     sudo judgeonce "$home" debug 1
+  done
+}
+while [ 1 ]
+do
+        judge_round $1
+done