[issue6721] Locks in python standard library should be sanitized on fork

[Nir Aides]

Nir Aides <nir at winpdb.org> added the comment:

Steffen, can you explain in layman's terms?

On Sun, May 15, 2011 at 8:03 PM, Steffen Daode Nurpmeso <report at bugs.python.org> wrote:
>
> @ Charles-François Natali wrote (2011-05-15 01:14+0200):
>> So if we really wanted to be safe, the only solution would be to
>> forbid fork() in a multi-threaded program.
>> Since it's not really a reasonable option
>
> But now - why this?  The only really acceptable thing if you have
> control about what you are doing is the following:
>
> class SMP::Process
>    /*!
>    * \brief Daemonize process.
>    *[.]
>    * \note
>    * The implementation of this function is not trivial.
>    * To avoid portability no-goes and other such problems,
>    * you may \e not call this function after you have initialized
>    * Thread::enableSMP(),
>    * nor may there (have) be(en) Child objects,
>    * nor may you have used an EventLoop!
>    * I.e., the process has to be a single threaded, "synchronous" one.
>    * [.]
>    */
>    pub static si32 daemonize(ui32 _daemon_flags=df_default);
>
> namespace SMP::POSIX
>    /*!
>    * \brief \fn fork(2).
>    *[.]
>    * Be aware that this passes by all \SMP and Child related code,
>    * i.e., this simply \e is the system-call.
>    * Signal::resetAllSignalStates() and Child::killAll() are thus if
>    * particular interest; thread handling is still entirely up to you.
>    */
>    pub static sir fork(void);
>
> Which kind of programs cannot be written with this restriction?

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<http://bugs.python.org/issue6721>
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