php curl json post在发送时被截断

$headers = array(
    'Content-Type: application/json',
);

$data = array(
    'key' => 'value',
    'key2' => 'value2',
);

$json_data = json_encode($data);

if ($json_data === false) {
    echo 'Invalid JSON data.';
    exit();
}

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POSTFIELDS, $json_data);

$result = curl_exec($ch);

if (curl_errno($ch)) {
    echo 'cURL error: ' . curl_error($ch);
} else {
    echo $result;
}

post_max_size = 100M
upload_max_filesize = 100M