[Lldb-commits] [lldb] r236892 - Enable thread-safe logging.

Pavel Labath labath at google.com
Mon May 11 08:40:28 PDT 2015

I think the reason is that when you are debugging a race condition,
the added synchronization resulting from logging can make the problem
go away as soon as you start investigating it, which can be quite

BTW, there is a way to do atomic writes (at least on posix systems, I
don't know if there is a windows equivalent) without locking: write
the string to a temporary buffer in memory (as you do now), and then
write it to a file which was opened with O_APPEND with a single system
call. Your implementation probably already does this, so all you need
to do is make sure O_APPEND is set.


On 11 May 2015 at 16:23, Zachary Turner <zturner at google.com> wrote:
> +greg. I'm not sure either tbh, if there's no contention the cost of
> acquiring the mutex should be free, and if there is contention then the lock
> is required.
> On Mon, May 11, 2015 at 7:29 AM Ed Maste <emaste at freebsd.org> wrote:
>> On 8 May 2015 at 14:50, Zachary Turner <zturner at google.com> wrote:
>> > Author: zturner
>> > Date: Fri May  8 13:50:54 2015
>> > New Revision: 236892
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=236892&view=rev
>> > Log:
>> > Enable thread-safe logging.
>> Thanks for fixing this up Zach.
>> This raises a question though, going back to the original introduction
>> of logging support -- why is this an option at all, never mind a user
>> facing option? It's particularly odd that we default to thread-safe,
>> unless any other options are specified. It seems to me we should just
>> remove the thread-unsafe path.
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