Add Java processBuilder demo

.github/workflows/demo_test.yml

@@ -103,7 +103,13 @@ jobs:
       run: docker exec java_support_test bash -c "cd /root/occlum/demos/java && occlum-javac ./hello_world/Main.java"
 
     - name: Run hello world
-      run: docker exec java_support_test bash -c "cd /root/occlum/demos/java && SGX_MODE=SIM ./run_java_on_occlum.sh hello" &
+      run: docker exec java_support_test bash -c "cd /root/occlum/demos/java && SGX_MODE=SIM ./run_java_on_occlum.sh hello"
+
+    - name: Compile processBuilder demo
+      run: docker exec java_support_test bash -c "cd /root/occlum/demos/java && occlum-javac ./processBuilder/processBuilder.java"
+
+    - name: Run processBuilder
+      run: docker exec java_support_test bash -c "cd /root/occlum/demos/java && SGX_MODE=SIM ./run_java_on_occlum.sh processBuilder"
 
   Fish_test:
     runs-on: ubuntu-18.04

.github/workflows/hw_mode_test.yml

@@ -288,6 +288,12 @@ jobs:
     - name: Run hello world
       run: docker exec $java_support_test bash -c "cd /root/occlum/demos/java && ./run_java_on_occlum.sh hello"
 
+    - name: Compile processBuilder demo
+      run: docker exec $java_support_test bash -c "cd /root/occlum/demos/java && occlum-javac ./processBuilder/processBuilder.java"
+
+    - name: Run processBuilder
+      run: docker exec $java_support_test bash -c "cd /root/occlum/demos/java && SGX_MODE=SIM ./run_java_on_occlum.sh processBuilder"
+
     - name: Clean the environment
       if: ${{ always() }}
       run: docker stop $java_support_test

demos/java/README.md

@@ -50,3 +50,23 @@ curl http://localhost:8080
 in another terminal.
 
 It is recommended to access the web application in a Web browser. You have to manually map port 8080 of the Docker container to a port on the host OS. Check out how to use [the `-p` argument of `docker run` command](https://docs.docker.com/engine/reference/commandline/run/).
+
+# Demo: ProcessBuilder application
+This demo shows that Occlum has enabled support for `ProcessBuilder` class and multiprocess in Java.
+
+# How to Run
+Step 1: Compile the source code with `occlum-javac`
+```
+occlum-javac ./processBuilder/processBuilder.java
+```
+When completed, the resulting file can be found at `./processBuilder/processBuilder.java`.
+
+Try to run it on native Linux with:
+```
+cd processBuilder && occlum-java processBuilder
+```
+
+Step 2: Start JVM to run the processBuilder demo
+```
+./run_java_on_occlum.sh processBuilder
+```

demos/java/processBuilder/processBuilder.java

@@ -0,0 +1,15 @@
+import java.io.IOException;
+
+public class processBuilder {
+    public static void main(String[] args) throws IOException, InterruptedException {
+
+    ProcessBuilder pb = new ProcessBuilder("date");
+    Process process = pb.start();
+
+    String result = new String(process.getInputStream().readAllBytes());
+    System.out.printf("%s", result);
+
+    var ret = process.waitFor();
+    System.out.printf("Child process exited with code: %d\n", ret);
+    }
+}

demos/java/run_java_on_occlum.sh

@@ -6,7 +6,7 @@ NC='\033[0m'
 
 show_usage() {
     echo "Error: invalid arguments"
-    echo "Usage: $0 web_app/hello"
+    echo "Usage: $0 web_app/hello/processBuilder"
     exit 1
 }
 
@@ -72,6 +72,29 @@ run_hello() {
     occlum run /usr/lib/jvm/java-11-alibaba-dragonwell/jre/bin/java -Xmx512m -XX:-UseCompressedOops -XX:MaxMetaspaceSize=64m -Dos.name=Linux Main
 }
 
+build_processBuilder() {
+    # Copy JVM and class file into Occlum instance and build
+    mkdir -p image/usr/lib/jvm
+    cp -r /opt/occlum/toolchains/jvm/java-11-alibaba-dragonwell image/usr/lib/jvm
+    cp /usr/local/occlum/x86_64-linux-musl/lib/libz.so.1 image/lib
+    cp ../${app} image
+    cp /bin/date image/bin/
+    # Need bigger user space size for multiprocess
+    new_json="$(jq '.resource_limits.user_space_size = "6000MB"' Occlum.json)" && \
+    echo "${new_json}" > Occlum.json
+    occlum build
+}
+
+run_processBuilder() {
+    app=./processBuilder/processBuilder.class
+    check_file_exist ${app}
+    init_instance
+    build_processBuilder
+    echo -e "${BLUE}occlum run JVM processBuilder${NC}"
+    occlum run /usr/lib/jvm/java-11-alibaba-dragonwell/jre/bin/java -Xmx512m -XX:-UseCompressedOops -XX:MaxMetaspaceSize=64m -Dos.name=Linux \
+        -Djdk.lang.Process.launchMechanism=posix_spawn processBuilder
+}
+
 arg=$1
 case "$arg" in
     web_app)
@@ -80,6 +103,9 @@ case "$arg" in
     hello)
         run_hello
         ;;
+    processBuilder)
+        run_processBuilder
+        ;;
     *)
         show_usage
 esac