SIGUSR2 from GC interrupts application system calls on Linux

[safety0ff via Digitalmars-d]

On Thursday, 26 May 2016 at 18:44:22 UTC, ikod wrote:
> Hello,
>
> On linux, in the code below, receive() returns -1 with 
> errno=EINTR if syscall is interrupted by GC (so you can see 
> several "insterrupted") when GC enabled, and prints nothing 
> (this is desired and expected behavior) when GC disabled.
>
> Is there any recommended workaround for this problem? Is this a 
> bug?

Looks like recv is non-restartable and it should be called in a 
loop.

>
> Looks like the reason of the problem is call sigaction(2) 
> without SA_RESTART for SIGUSR2 (used by GC to restart suspended 
> thread) in core.thread.

This isn't the cause, manually adding SA_RESTART using sigaction 
made no difference:

     import core.sys.posix.signal;
     sigaction_t tmp;
     sigaction(SIGUSR2, null, &tmp);
     tmp.sa_flags |= SA_RESTART;
     sigaction(SIGUSR2, &tmp, null);

This is because SIGUSR1 is the signal that actually interrupts 
the system call, when SIGUSR2 is received the syscall is already 
interrupted so the flag does not make a difference.