Segmentation fault in NvJPEGEncoder::encodeFromBuffer when encoder accessed from multiple threads

[nitzuas961]

Hi,

The program:

#include <vector>
#include <memory>
#include <mutex>
#include <thread>

#include <NvJpegEncoder.h>

std::recursive_mutex cmut;

bool encode_yuv(std::unique_ptr<NvJPEGEncoder>& encoder,
                uint8_t* bufY,
                uint8_t* bufU,
                uint8_t* bufV,
                const uint16_t height,
                const uint16_t width,
                std::vector<uint8_t> &outBuf,
                uint8_t quality = 80)
{
  const std::lock_guard<std::recursive_mutex> lock(cmut);

  if (!encoder)
  {
    return false;
  }

  quality = std::min(quality, static_cast<uint8_t>(100));

  NvBuffer buffer(V4L2_PIX_FMT_YUV420M, width, height, 0);

  buffer.planes[0].data = bufY;
  buffer.planes[0].bytesused = width * height;

  buffer.planes[1].data = bufU;
  buffer.planes[1].bytesused = width * height / 4;

  buffer.planes[2].data = bufV;
  buffer.planes[2].bytesused = width * height / 4;

  uint64_t outBufSize = 3 * width * height / 2;
  outBuf.resize(outBufSize);
  auto outBufPtr = outBuf.data();

  if (encoder->encodeFromBuffer(buffer, JCS_YCbCr, &outBufPtr, outBufSize, quality) < 0)
  {
    return false;
  }

  outBuf.resize(outBufSize);
  return true;
}

void run(std::unique_ptr<NvJPEGEncoder>& encoder)
{
  int cols = 256;
  int rows = 256;

  std::vector<uint8_t> channel0(rows*cols, 1);
  std::vector<uint8_t> channel1((rows/2)*(cols/2), 2);
  std::vector<uint8_t> channel2((rows/2)*(cols/2), 3);

  std::vector<uint8_t> out_jpeg;
  
  std::cout << encode_yuv(
    encoder,
    channel0.data(),
    channel1.data(),
    channel2.data(),
    rows, cols,
    out_jpeg
  ) << std::endl;
}

int main()
{
  std::unique_ptr<NvJPEGEncoder> encoder = std::unique_ptr<NvJPEGEncoder>(NvJPEGEncoder::createJPEGEncoder("jpenenc"));
  std::vector<std::thread> thr;

  for (int i = 0; i < 30; i++)
  {
    thr.push_back(
      std::thread(run, std::ref(encoder))
    );
  }

  for(auto &t: thr)
  {
		t.join();
  }

  return 0;
}

fails with segfault and the following back trace:

(signal SIGSEGV), 0x0000ffffb160fac4 in ?? () from /usr/lib/aarch64-linux-gnu/tegra/libnvvideo.so
#0  0x0000ffffb160fac4 in ?? () from /usr/lib/aarch64-linux-gnu/tegra/libnvvideo.so
#1  0x0000ffffb14432d0 in ?? () from /usr/lib/aarch64-linux-gnu/tegra/libnvmmlite_image.so
#2  0x0000ffffb1443694 in ?? () from /usr/lib/aarch64-linux-gnu/tegra/libnvmmlite_image.so
#3  0x0000ffffee3213b8 in NvMMLiteBlockDoWork () from /usr/lib/aarch64-linux-gnu/tegra/libnvmmlite_utils.so
#4  0x0000ffffee334be0 in ?? () from /usr/lib/aarch64-linux-gnu/tegra/libnvmmlite.so
#5  0x0000fffff7fa56a4 in jpegTegraEncoderCompress () from /usr/lib/aarch64-linux-gnu/tegra/libnvjpeg.so
#6  0x0000fffff7f6bc08 in jpeg_write_raw_data () from /usr/lib/aarch64-linux-gnu/tegra/libnvjpeg.so
#7  0x0000aaaaaada416c in NvJPEGEncoder::encodeFromBuffer (this=0xaaaaabb4ac20, buffer=..., color_space=<optimized out>, out_buf=<optimized out>, out_buf_size=<optimized out>, quality=<optimized out>)
    at /rootfs_arm64/usr/src/jetson_multimedia_api/samples/common/classes/NvJpegEncoder.cpp:258

Could you please help to check this issue? Thanks.

The jetpack version is 5.1.3.

[DaneLLL]

Hi,
Please create individual NvJPEGEncoder object for each thread. Or if you would like to use singe object, please use mutex to ensure encodeFromBuffer() is sequentially called(to avoid calling it concurrently).

[nitzuas961]

Hi,

I would like to use a single object. In the provided code encodeFromBuffer() is already inside the critical section (locked with the mutex in the beginning of the encode_yuv() function). Nevertheless, this does not prevent aforementioned segfault. Could you please tell whether any additional syncronization primitive required or generally is there anything else missing?