我自己无法调试一个错误。我在Fedora release 35（Thirty Five）上的docker镜像中运行python 3.8.12，无法从python生成线程。boto3传输需要并行运行，它使用concurrent.features来实现。
复制我的问题而没有任何依赖关系的最简单的例子是（从python文档复制）

import concurrent.futures
import urllib.request

URLS = ['http://www.foxnews.com/',
        'http://www.cnn.com/',
        'http://europe.wsj.com/',
        'http://www.bbc.co.uk/',
        'http://some-made-up-domain.com/']

def load_url(url, timeout):
    with urllib.request.urlopen(url, timeout=timeout) as conn:
        return conn.read()

with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:
    future_to_url = {executor.submit(load_url, url, 60): url for url in URLS}
    for future in concurrent.futures.as_completed(future_to_url):
        url = future_to_url[future]
        try:
            data = future.result()
        except Exception as exc:
            pass

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遗憾的是，这些行的输出是

Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "<stdin>", line 2, in <dictcomp>
  File "/usr/lib64/python3.8/concurrent/futures/thread.py", line 188, in submit
    self._adjust_thread_count()
  File "/usr/lib64/python3.8/concurrent/futures/thread.py", line 213, in _adjust_thread_count
    t.start()
  File "/usr/lib64/python3.8/threading.py", line 852, in start
    _start_new_thread(self._bootstrap, ())
RuntimeError: can't start new thread

型
这就是我所有的。有地方我应该看看吗？我已经检查了ulimit，上面写着unlimited。我有点绝望，在哪里寻找或改变什么来调试这个问题。