Ahh wait, sorry. I meant posix_spawn, not execve On Mon, Oct 16, 2017 at 2:16 PM Zachary Turner <ztur...@google.com> wrote:
> I guess what I mean is, my understanding is that the only "advantage" (if > you can even call it that) of using fork + exec over execve is that fork + > exec allows you to run additional code between the fork and the exec. > > Do we actually rely on that? Why do we need it to do fork at all? Why > can't we just execve from the parent process without doing a fork at all? > > On Mon, Oct 16, 2017 at 2:06 PM Tamas Berghammer <tbergham...@google.com> > wrote: > >> On linux when you call fork the new process will only have the thread >> what called fork. Other threads will be ignored with leaving whatever dirty >> state they had left in the new process. Regarding execve it doesn't do fork >> so we would have to do fork & execve what have the same issue (actually we >> are using execve as of now but it isn't different from exec in this regard). >> >> Tamas >> >> On Mon, Oct 16, 2017 at 1:57 PM Zachary Turner via lldb-commits < >> lldb-commits@lists.llvm.org> wrote: >> >>> On Sun, Oct 15, 2017 at 3:15 PM Pavel Labath <lab...@google.com> wrote: >>> >>>> On 15 October 2017 at 23:04, Zachary Turner <ztur...@google.com> wrote: >>>> > Doesn’t DisableAllLogChannels acquire a scoped lock? If so wouldn’t >>>> it just >>>> > release at the end of the function? >>>> >>>> >>>> The thing is, it is unable to acquire the lock in the first place, >>>> because the mutex is already "locked". So, the sequence of events is >>>> process 1, thread 1: acquire lock >>>> process 1, thread 2: fork(), process 2 is created >>>> process 1 thread 1: release lock >>>> >>> >>> Suppose process 1 thread 1 had been executing this code: >>> ``` >>> lock(); >>> logSomething(); // thread 2 forks when thread 1 is here. >>> unlock(); >>> ``` >>> >>> Doesn't thread 2 in the child process resume running from the same >>> point? If so, it seems that both the child and parent would both >>> gracefully unlock the lock. >>> >>> I'm sure I'm wrong about this, but hopefully you can clarify what I'm >>> missing. >>> >>> As a follow-up question, why can't we use execve instead of fork / exec? >>> >> _______________________________________________ >>> lldb-commits mailing list >>> lldb-commits@lists.llvm.org >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits >>> >>
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