marcogovo's profile - activity

Hi guys,

My research team and i are working on a JRuby multithreaded application, that calls in an on-demand way a simple java class for face-recognition.

• the JVM is always Oracle jdk 1.8.0_121
• the JRuby version is always jruby 9.1.7.0

About openCV, we have tested the 3.2.0 and 3.1.0 versions, building it with java bindings in the following way:

cmake -DMAKE_BUILD_TYPE=DEBUG -DBUILD_SHARED_LIBS=OFF

putting opencv_320.jar in /usr/share/java, and libopencv_java3**.so in /usr/local/lib .

The java code is the following ( we use two face-detectors ):

public class FaceRecognition {

  static{
    System.load("/usr/local/lib/libopencv_java310.so");
  }

  public static String doFaceRec(byte[] img_stream) {
    Mat frame = Imgcodecs.imdecode(new MatOfByte(img_stream), Imgcodecs.IMREAD_UNCHANGED);
    CascadeClassifier faceDetector1 = new CascadeClassifier("haarcascade_profileface.xml");
    faceDetector1.load("haarcascade_profileface.xml");
    CascadeClassifier faceDetector2 = new CascadeClassifier("haarcascade_frontalface_alt.xml");
    faceDetector2.load("haarcascade_frontalface_alt.xml");
    if (faceDetector1.empty() || faceDetector2.empty()) {
        frame.release();
System.out.println("faceDetector is empty");
        return "0";
    }

    MatOfRect faceDetections = new MatOfRect();
    MatOfRect faceDetections2 = new MatOfRect();
    faceDetector1.detectMultiScale(frame, faceDetections, 1.3, 3, 0, new Size(), new Size());
    faceDetector2.detectMultiScale(frame, faceDetections2, 1.1, 3, 0, new Size(), new Size());

    int found = faceDetections.toArray().length + faceDetections2.toArray().length;
    faceDetections.release();
    faceDetections2.release();
    frame.release();

    return ""+found;
  }
}

The application generates different threads that call the doFaceRec(..) method provided by FaceRecognition class; through a concurrent-lock mechanism we are sure that only one thread per time calls the doFaceRec(..) method.

We tested the application on different machines with same conditions and/or parameters, with no errors:

• Raspberry Pi 3 (quad-core, 1GB of RAM), Raspbian 8.0 / linux 4.4.38
• Sony vaio (i7 dual-core, 12GB of RAM) Ubuntu 16.04 / linux 4.4.0
• Dell XPS 13 9360 (i7 dual-core, 16GB of RAM), Ubuntu 16.04 / linux 4.8.4

Unfortunately, we had some errors testing the code in other machines:

• Lenovo with i7 quad-core processor, 16GB of RAM, the only machine with openjdk 8
• Amazon m4.4xlarge EC2 instance (Intel Xeon 16 vCPU, 64gb of RAM) Ubuntu 16.04 / linux 4.4.0

Without any limitation on the number of used threads, and using both opencv 3.2.0 and opencv 3.1.0 , we have two different errors ( we show only the errors on opencv3.2.0 because those with opencv3.1.0 are the same ):

Error 1:

[thread 140705678751488 also had an error][thread 140706560714496 also had an error][thread 140705812969216 also had an error][thread 140705804576512 also had an error][thread 140705787791104 also had an error]#

# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007ff8dcb7bdcb, pid=3047, tid=0x00007ff89effd700
#
# JRE version: Java(TM) SE Runtime Environment (8.0_121-b13) (build 1.8.0_121-b13)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.121-b13 mixed mode linux-amd64 compressed oops)
# Problematic frame:
# java: /dev/opencv/opencv-3.2.0/modules/objdetect/src/cascadedetect.cpp:922: int cv::CascadeClassifierImpl::runAt(cv::Ptr<cv::FeatureEvaluator>&, cv::Point, int, double&): Assertion `!oldCascade && (data.featureType == FeatureEvaluator::HAAR || data.featureType == FeatureEvaluator ...