本文主要是介绍pip总是报Segmentation fault (core dumped)的问题（安装python新版本3.9.6后），对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

问题描述

一开始使用pyenv安装了python 3.9.6版本之后，pyenv居然失灵了，切换不到任何版本去了，一气之下，删掉pyenv（rm -rf ~/.pyenv）直接源码安装。

步骤如下：

1. 到官网https://www.python.org/downloads/下载最新的tar包

2. 解压后执行：

    ./configure --prefix=/opt/python-3.9.6
    make
    make install
   

3. 安装完成后，pip不能正常使用，即便是查看已安装包都会出现core dump

    $ python3 -V
    Python 3.9.6
    $ pip3 list
    Package    Version
    ---------- -------
    pip        21.1.3
    setuptools 56.0.0
    Segmentation fault (core dumped)
    $ python3 -m pip list
    Package    Version
    ---------- -------
    pip        21.1.3
    setuptools 56.0.0
    Segmentation fault (core dumped)
   

解决方法

找了半天没有找到答案，最后只能硬着头皮去调试pip3的代码，结果发现跟SSL有关（后面会描述如何发现的，这里先说解决方法）。

官网https://www.python.org/dev/peps/pep-0644/也说了要求OpenSSL 1.1.1及以上版本（“Require OpenSSL 1.1.1 or newer”），而我自己机器上的是1.1.0版本的。

$ openssl version
OpenSSL 1.1.0h-fips  27 Mar 2018

解决办法：

1. 到OpenSSL官网https://www.openssl.org/source/下载1.1.1版本的tar包

2. 解压后执行：

    ./config
    make
    make install
   

3. 安装完成后，查看OpenSSL版本报错：

    $ openssl version
    openssl: /usr/lib64/libssl.so.1.1: version `OPENSSL_1_1_1' not found (required by openssl)
    openssl: /usr/lib64/libcrypto.so.1.1: version `OPENSSL_1_1_1' not found (required by openssl)
   

   解决办法：

    export LD_LIBRARY_PATH=/usr/local/lib64    # 最好写入 ~/.bashrc 或 /etc/profile 中去
    $ openssl version
    OpenSSL 1.1.1k  25 Mar 2021
   

4. 这个时候以为问题解决了，重新执行 pip3 list 仍然会出现 core dump，折腾了一天，差点都想放弃了，后来一想，python编译时链接的还是原来的旧库，所有需要重新编译python。回到 python 源码解压目录执行：

    make distclean    # 把上一次编译过程中留下的余孽清理干净
    ./configure --prefix=/opt/python-3.9.6
    make
    make install
   

5. 完事后，再试，大功告成！

    $ pip3 list
    Package    Version
    ---------- -------
    pip        21.2.1
    setuptools 56.0.0
    $ python3 -m pip list
    Package    Version
    ---------- -------
    pip        21.2.1
    setuptools 56.0.0
    $ pip list
    Package    Version
    ---------- -------
    pip        21.2.1
    setuptools 56.0.0
   

分析过程

1. 网上搜答案，没有雷同的，苦恼！

2. 想尝试去调试Core dump吧，即便执行了 ulimit -c unlimited ，也不会在当前目录中生成 core file，最后发现 core file 在下面这个目录，汗！

    /var/lib/systemd/coredump
   

3. 有了 core file，咋调试？ 执行 gdb /opt/python-3.9.6/bin/pip3 core-file 根本就打印不出 backtrace 出来，因为 pip3 本身是个 python 文本文件，而不是二进制可执行程序。

4. 好吧，调试 pip3 这个 python 文件：

    $ python -m pdb /opt/python-3.9.6/bin/pip3 list
    > /opt/python-3.9.6/bin/pip3(3)<module>()
    -> import re
    (Pdb) b /opt/python-3.9.6/lib/python3.9/ssl.py:483
    Breakpoint 1 at /opt/python-3.9.6/lib/python3.9/ssl.py:483
    (Pdb) c
    Package    Version
    ---------- -------
    pip        21.1.3
    setuptools 56.0.0
    > /opt/python-3.9.6/lib/python3.9/ssl.py(483)__new__()
    -> self = _SSLContext.__new__(cls, protocol)
    (Pdb) where
      /opt/python-3.9.6/lib/python3.9/bdb.py(580)run()
    -> exec(cmd, globals, locals)
      <string>(1)<module>()
      /opt/python-3.9.6/bin/pip3(8)<module>()
    -> sys.exit(main())
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/cli/main.py(71)main()
    -> return command.main(cmd_args)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/cli/base_command.py(104)main()
    -> return self._main(args)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/cli/base_command.py(221)_main()
    -> self.handle_pip_version_check(options)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/cli/req_command.py(147)handle_pip_version_check()
    -> pip_self_version_check(session, options)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/self_outdated_check.py(152)pip_self_version_check()
    -> best_candidate = finder.find_best_candidate("pip").best_candidate
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/index/package_finder.py(879)find_best_candidate()
    -> candidates = self.find_all_candidates(project_name)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/index/package_finder.py(824)find_all_candidates()
    -> page_candidates = list(page_candidates_it)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/index/sources.py(134)page_candidates()
    -> yield from self._candidates_from_page(self._link)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/index/package_finder.py(783)process_project_url()
    -> html_page = self._link_collector.fetch_page(project_url)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/index/collector.py(512)fetch_page()
    -> return _get_html_page(location, session=self.session)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/index/collector.py(422)_get_html_page()
    -> resp = _get_html_response(url, session=session)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/index/collector.py(120)_get_html_response()
    -> resp = session.get(
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/requests/sessions.py(555)get()
    -> return self.request('GET', url, **kwargs)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_internal/network/session.py(449)request()
    -> return super().request(method, url, *args, **kwargs)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/requests/sessions.py(542)request()
    -> resp = self.send(prep, **send_kwargs)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/requests/sessions.py(655)send()
    -> r = adapter.send(request, **kwargs)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/cachecontrol/adapter.py(53)send()
    -> resp = super(CacheControlAdapter, self).send(request, **kw)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/requests/adapters.py(439)send()
    -> resp = conn.urlopen(
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/urllib3/connectionpool.py(699)urlopen()
    -> httplib_response = self._make_request(
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/urllib3/connectionpool.py(382)_make_request()
    -> self._validate_conn(conn)
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/urllib3/connectionpool.py(1010)_validate_conn()
    -> conn.connect()
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/urllib3/connection.py(392)connect()
    -> self.ssl_context = create_urllib3_context(
      /opt/python-3.9.6/lib/python3.9/site-packages/pip/_vendor/urllib3/util/ssl_.py(281)create_urllib3_context()
    -> context = SSLContext(ssl_version or PROTOCOL_TLS)
    > /opt/python-3.9.6/lib/python3.9/ssl.py(483)__new__()
    -> self = _SSLContext.__new__(cls, protocol)    <=========== 这里已经进不去了，core就出现在这一步，看名字就是跟SSL有关吧
    (Pdb) p cls
    <class 'ssl.SSLContext'>
    (Pdb) p protocol
    <_SSLMethod.PROTOCOL_TLS: 2>
    (Pdb) s
    Segmentation fault (core dumped)
   

5. 看到SSL立马去搜 python +SSL 关键字，才发现官网的这个说明https://www.python.org/dev/peps/pep-0644/，也就有了去尝试安装 OpenSSL 1.1.1 的想法。

这一切的一切都源于本来想安装 pypiwin32 这个包，想用它来分析windows系统日志，windows上装成功了，linux上没有装成功，然后以为是旧版本的问题去装新版本，折腾了一天，烧死多少脑细胞，就搞个环境问题，不过，生命在于折腾嘛！

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