[Lldb-commits] [PATCH] fix lldb-mi hang on OSX

[Zachary Turner]

I kind of feel like calling fgets from one thread and fileno from another
thread indicates a design flaw. Is there any way to fix the design problem
instead of this particular bug?
On Tue, Dec 2, 2014 at 1:24 AM Илья К <ki.stfu at gmail.com> wrote:

> Hello Abid,
>
> >RE: But I am still wondering why you need extra "return" in case of
> -exec-run. It seems to work ok on Linux. Where is it blocking in OSX?
> I had the same bug on OSX but "select" patch helped me (btw, thank Dawn
> for that).
> As I understood the problem occurs when trying to get filno(stdin), when
> another thread sleeping in fgets(stdin). The filno() starts sleeping too
> because stdin's mutex already locked by fgets(). Perhaps it related to
> OSX's libc implementation and therefore it don't reproduced on Linux.
>
> I wrote test, which doesn't works properly without WITH_SELECT_FIX:
> <code>
> #include <cstdio>
> #include <thread>
> #include <unistd.h>
> #include <sys/select.h>
>
> //#define WITH_SELECT_FIX
>
> void first_func()
> {
>     char buf[1024];
> #ifdef WITH_SELECT_FIX
>     fd_set inset;
>     FD_ZERO(&inset);
>     FD_SET(0, &inset);
>     select(1, &inset, NULL, NULL, NULL);
> #endif
>     char *line = fgets(buf, sizeof buf, stdin);
>     printf("you entered: %s\n", buf);
> }
>
> void second_func()
> {
>     usleep(100);
>     printf("fileno: ");
>     printf("%d\n", fileno(stdin));
> }
>
> int main()
> {
>     std::thread first(first_func);
>     std::thread second(second_func);
>     printf("start test\n");
>     first.join();
>     second.join();
>     printf("exiting\n");
>     return 0;
> }
> </code>
>
> >RE: Btw, if the problem is only with gdb-exit then an extra check for it
> where we check for "quit" will work too.
> As I said above, it doesn't solve a problem, it only fixes a certain case.
>
> So I think you should accept the Dawn's "select" patch.
>
> Thanks,
> Ilia
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