diff --git a/.gitignore b/.gitignore
index b14852c..2686a19 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 api/api
+lxc/i
diff --git a/lxc/execute b/lxc/execute
index 0fe3ee9..83f9378 100755
--- a/lxc/execute
+++ b/lxc/execute
@@ -24,6 +24,17 @@ chmod 777 $basepath/tmp/$epoch
 cat $2 > $basepath$filepath
 echo "${@:3}" > $basepath$argpath
 
+# process incrementor
+oldinc=$(cat $dir/i | awk '{$1=$1};1')
+newinc=$(expr $oldinc + 1)
+
+if (( newinc >= 151 )); then
+    newinc=1
+    echo 1 > $dir/i
+else
+    echo $newinc > $dir/i
+fi
+
 bin=
 case "$lang" in
 "python2")
@@ -67,7 +78,14 @@ case "$lang" in
     exit
 esac
 
+# runner
 lxc-attach -n piston -- \
-    /bin/bash -c "PATH=/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin bash /exec/$bin $epoch 2>&1 | head -c 65536"
+    /bin/bash -c "\
+        PATH=/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin \
+        bash /exec/$bin $newinc $epoch 2>&1 | head -c 65536"
+
+# process janitor
+lxc-attach -n piston -- \
+    /bin/bash -c "for i in {1..2000}; do pkill -u runner$newinc --signal SIGKILL; done" > /dev/null 2>&1 &
 
 rm -rf $basepath/tmp/$epoch
diff --git a/lxc/executors/c b/lxc/executors/c
index 10a96be..0cd5424 100755
--- a/lxc/executors/c
+++ b/lxc/executors/c
@@ -1,3 +1,3 @@
-cd /tmp/$1
+cd /tmp/$2
 timeout -s KILL 10 gcc -o binary -x c code.code
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' ./binary"
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 ./binary"
diff --git a/lxc/executors/cpp b/lxc/executors/cpp
index cbe90ab..64a5157 100755
--- a/lxc/executors/cpp
+++ b/lxc/executors/cpp
@@ -1,3 +1,3 @@
-cd /tmp/$1
+cd /tmp/$2
 timeout -s KILL 10 g++ -o binary -x c++ code.code
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' ./binary"
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 ./binary"
diff --git a/lxc/executors/csharp b/lxc/executors/csharp
index 20691be..ec47c4a 100755
--- a/lxc/executors/csharp
+++ b/lxc/executors/csharp
@@ -1,3 +1,3 @@
-cd /tmp/$1
+cd /tmp/$2
 timeout -s KILL 10 mcs $(echo code.code | sed 's/\///') -out:binary
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' mono binary"
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 mono binary"
diff --git a/lxc/executors/go b/lxc/executors/go
index 0963669..5084a30 100755
--- a/lxc/executors/go
+++ b/lxc/executors/go
@@ -1,6 +1,6 @@
-cd /tmp/$1
+cd /tmp/$2
 cp code.code interim.go
 file="interim.go"
 GOROOT=/usr/lib/go timeout -s KILL 10 go build $file
 file=${file%%.*}
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' ./$file"
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 ./$file"
diff --git a/lxc/executors/java b/lxc/executors/java
index 11b500a..7c8d1ff 100755
--- a/lxc/executors/java
+++ b/lxc/executors/java
@@ -1,6 +1,6 @@
-cd /tmp/$1
+cd /tmp/$2
 cp code.code interim.java
 name=$(cat interim.java | grep -Eo 'public\s+class\s+([A-Za-z0-9]+)' | sed -n 's/  */ /gp' | cut -d' ' -f3)
 mv interim.java $name.java
 timeout -s KILL 10 javac $name.java
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' java $name"
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 java $name"
diff --git a/lxc/executors/nasm b/lxc/executors/nasm
index ebacda1..661db6c 100755
--- a/lxc/executors/nasm
+++ b/lxc/executors/nasm
@@ -1,4 +1,4 @@
-cd /tmp/$1
+cd /tmp/$2
 timeout -s KILL 10 nasm -f elf64 -o binary.o code.code
 timeout -s KILL 10 ld binary.o -o binary
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' ./binary"
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 ./binary"
diff --git a/lxc/executors/node b/lxc/executors/node
index 8f88431..73c2f80 100755
--- a/lxc/executors/node
+++ b/lxc/executors/node
@@ -1,2 +1,2 @@
-cd /tmp/$1
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' nodejs code.code"
+cd /tmp/$2
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 nodejs code.code"
diff --git a/lxc/executors/php b/lxc/executors/php
index dc26d43..5731b85 100755
--- a/lxc/executors/php
+++ b/lxc/executors/php
@@ -1,2 +1,2 @@
-cd /tmp/$1
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' php code.code"
+cd /tmp/$2
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 php code.code"
diff --git a/lxc/executors/python2 b/lxc/executors/python2
index 38f4cf6..8ccb484 100755
--- a/lxc/executors/python2
+++ b/lxc/executors/python2
@@ -1,2 +1,2 @@
-cd /tmp/$1
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' python2 code.code"
+cd /tmp/$2
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 python2 code.code"
diff --git a/lxc/executors/python3 b/lxc/executors/python3
index e71d7fc..ef5b036 100755
--- a/lxc/executors/python3
+++ b/lxc/executors/python3
@@ -1,2 +1,2 @@
-cd /tmp/$1
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' python3.6 code.code"
+cd /tmp/$2
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 python3.6 code.code"
diff --git a/lxc/executors/r b/lxc/executors/r
index 39810fd..b12ee07 100755
--- a/lxc/executors/r
+++ b/lxc/executors/r
@@ -1,2 +1,2 @@
-cd /tmp/$1
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' Rscript code.code"
+cd /tmp/$2
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 Rscript code.code"
diff --git a/lxc/executors/ruby b/lxc/executors/ruby
index f9bd9dd..11b12b2 100755
--- a/lxc/executors/ruby
+++ b/lxc/executors/ruby
@@ -1,2 +1,2 @@
-cd /tmp/$1
-timeout -s KILL 3 runuser ubuntu -c "cat args.args | xargs -d '\n' ruby code.code"
+cd /tmp/$2
+runuser -l runner$1 -c "cd /tmp/$2 ; cat args.args | xargs -d '\n' timeout -s KILL 3 ruby code.code"
diff --git a/lxc/notes.txt b/lxc/notes.txt
index 947db35..685c40b 100644
--- a/lxc/notes.txt
+++ b/lxc/notes.txt
@@ -15,11 +15,16 @@ sed -i 's/http:\/\/archive.ubuntu.com\/ubuntu/http:\/\/mirror.math.princeton.edu
 apt-get update
 apt-get -y install tzdata nano dpkg-dev build-essential python python3 ruby nodejs golang php7.2 r-base mono-complete nasm openjdk-8-jdk
 
-# apply limits
-echo 'ubuntu soft nproc 16' >> /etc/security/limits.conf
-echo 'ubuntu hard nproc 16' >> /etc/security/limits.conf
-echo 'ubuntu soft nofile 1024' >> /etc/security/limits.conf
-echo 'ubuntu hard nofile 1024' >> /etc/security/limits.conf
+# create users and apply limits
+for i in {1..150}; do
+    #userdel runner$i
+    useradd -M runner$i
+    usermod -d /tmp runner$i
+    echo "runner$i soft nproc 64" >> /etc/security/limits.conf
+    echo "runner$i hard nproc 64" >> /etc/security/limits.conf
+    echo "runner$i soft nofile 2048" >> /etc/security/limits.conf
+    echo "runner$i hard nofile 2048" >> /etc/security/limits.conf
+done
 
 # remove home dir
 rm -rf /home/ubuntu