通过 child_process 从 Python 向节点发送 JSON 如果太长会被截断，如何解决？

Question

我的节点和 Python 后端运行很好，但我现在遇到一个问题，如果 JSON 我从 Python 返回没有节点太长了，它被分成两部分，我在节点端的 JSON.parse 失败了。

我应该如何解决这个问题？比如第一批剪辑在

... [1137.6962355826706, -100.78015825640887], [773.3834338399517, -198

第二个还有剩下的几条

.201506231888], [-87276.575065248, -60597.8827676457], [793.1850250453127, 
-192.1674702207991], [1139.4465453979683, -100.56741252031816], 
[780.498416769341, -196.04064849430705]]}

我是否必须在节点端创建一些长时间 JSONs 的逻辑，或者这是我在 Python 端遇到的某种缓冲问题，我可以通过正确设置？这是我在 python 方面所做的一切：

outPoints, _ = cv2.projectPoints(inPoints, np.asarray(rvec), 
np.asarray(tvec), np.asarray(camera_matrix), np.asarray(dist_coeffs))

# flatten the output to get rid of double brackets per result before JSONifying
flattened = [val for sublist in outPoints for val in sublist]
print(json.dumps({'testdata':np.asarray(flattened).tolist()}))
sys.stdout.flush()

在节点端：

// Handle python data from print() function
  pythonProcess.stdout.on('data', function (data){

    try {
      // If JSON handle the data
      console.log(JSON.parse(data.toString()));
    } catch (e) {
      // Otherwise treat as a log entry
      console.log(data.toString());
    }
  });

Answer 1

发出的数据是分块的，所以如果你想解析一个 JSON 你将需要加入所有的块，并在 end 上执行 JSON.parse.

By default, pipes for stdin, stdout, and stderr are established between the parent Node.js process and the spawned child. These pipes have limited (and platform-specific) capacity. If the child process writes to stdout in excess of that limit without the output being captured, the child process will block waiting for the pipe buffer to accept more data.

在 linux 中，每个块限制为 65536 字节。

In Linux versions before 2.6.11, the capacity of a pipe was the same as the system page size (e.g., 4096 bytes on i386). Since Linux 2.6.11, the pipe capacity is 65536 bytes.

let result = '';
pythonProcess.stdout.on('data', data => {
    result += data.toString();
    // Or Buffer.concat if you prefer.
});

pythonProcess.stdout.on('end', () => {
    try {
      // If JSON handle the data
      console.log(JSON.parse(result));
    } catch (e) {
      // Otherwise treat as a log entry
      console.log(result);
    }
});

通过 child_process 从 Python 向节点发送 JSON 如果太长会被截断，如何解决？

Sending JSON from Python to Node via child_process gets truncated if too long, how to fix?

python

stdout

child-process

node.js