Re: [boost] [interprocess] Boost.Thread developers willing to help on interprocess condition vars?

From: Phil Endecott (spam_from_boost_dev_at_[hidden])
Date: 2007-09-28 10:55:05

Anthony Williams wrote:
> Ion Gazta?aga <igaztanaga_at_[hidden]> writes:
>> Peter Dimov wrote:
>>> Ion Gazta?aga wrote:
>>>
>>>> Does this support building those objects in mapped files, rebooting
>>>> the system, mapping the file again again and continue working?
[snip]
> However, I would not expect the mutex to survive a reboot --- there might
> still be data in the file, but I would expect a process-shared mutex to have
> at least some portion that was a handle to a kernel object, and the kernel
> object would go away with a reboot.

I have no idea what the POSIX spec requires or what most 
implementations actually do.  But I believe that the Linux 
implementation, using the futex() system call, probably can survive a 
reboot as it has no permanent kernel component.  The kernel only gets 
involved when a process finds the mutex locked, and needs to wait.  See 
'man 2 futex'.  Of course the pthread_* functions, which wrap the 
futex() functionality, may make it impossible to exploit this behaviour.

Phil.