[lldb-dev] How does attach work on non-Windows?

[Greg Clayton via lldb-dev]

Or is this just a problem with a bad test? Are we telling LLDB to launch the test and LLDB is doing the launch + attach in the windows platform and that is what is hosing up the attach? Or is this a flawed test where the test just manually launches the process with no hopes of syncing with the process we are attaching to?

> On Aug 31, 2015, at 3:16 PM, Greg Clayton via lldb-dev <lldb-dev at lists.llvm.org> wrote:
> 
> So a few things:
> 
> 1 - on MacOSX we can reliably launch a process via posix_spawn() with a flag set that sets the process to stop at __dyld_start which is the first instruction in the program. So our launch then attach always works reliably because when we launch the process set set this posix_spawn() flag.
> 
> 2 - on linux I believe this is solved by doing a manual fork(), sync(), exec().
> 
> 3 - on windows we have a sync problem for the launch first then attach due to this extra thread. Is this the case?
> 
> Seems like you should be able to launch with Use the CreateProcess() function, set CREATE_SUSPENDED and then attach no?
> 
> I would rather not solve this problem that is windows only by requiring that all test suite functions link to a .a file. We should be able to launch a process and debug it using the launch then attach method that is used by our platform.
> 
> Greg
> 
> 
> 
>> On Aug 27, 2015, at 4:04 PM, via lldb-dev <lldb-dev at lists.llvm.org> wrote:
>> 
>> On Thu, Aug 27, 2015 at 10:17:24PM +0000, Zachary Turner wrote:
>>> In what instances do you think it wouldn't work?  At least on Windows it's
>>> trivial.  Jim provided some code that would work on OSX, and someone else
>>> provided a method earlier in the thread that should work for Linux.  What
>>> are the specific reliability concerns you have?
>> 
>> I'm basing this off our own experiences - we use a similar method to
>> test Android and iOS platforms, and they work most of the time, but fail
>> randomly, about once every 25 runs, because one of the 50 or so test
>> cases couldn't sync up with the debug server on the device.  Do other
>> people see similar problems?
>> 
>> If you're running the tests natively, I bet you'll be fine.
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