Issues with Socket.accept() and SIGUSR1

[LeqxLeqx]

On Friday, 8 December 2017 at 23:11:47 UTC, Adam D. Ruppe wrote:
> On Friday, 8 December 2017 at 22:27:41 UTC, LeqxLeqx wrote:
>> Normally the accept will throw a timeout and then the loop 
>> will continue to listen, but sometimes (and I can't find a 
>> decent pattern) the Socket.accept() method will raise a 
>> SIGUSR1 rather than throwing an exception of any kind.
>
> That probably means the *other* thread started a garbage 
> collection cycle. The D GC uses that signal to pause threads 
> while it scans memory, so they don't change out from under it 
> mid-scan.
>
> All you need to do is try the accept again if that happens. It 
> isn't really an exception, it is just an EINTR - signal call 
> interrupted - and you are supposed to just try again when that 
> happens (unless the interruption meant the program is now 
> instructed to terminate e.g. SIGINT)

Than you both for answering my stupid question.

Nonetheless, it seems that there still is a very strange thing 
going on. I'm getting a segfault (which was the error I got 
before I opened GDB and ran into the SIGUSR1 thing), in the 
middle of a object.opEquals call. It seems to be triggered right 
after the GC's SIGUSR1.

Perhaps this is just another stupid question, but is it possible 
that the D GC is collecting a resource which my program is still 
attempting to use? I'm not using pointers directly at all in this 
program.



   Thread 2 "sverse" received signal SIGUSR1, User defined signal 
1.

   Thread 3 "sverse" received signal SIGUSR1, User defined signal 
1.

   Thread 2 "sverse" received signal SIGUSR2, User defined signal 
2.

   Thread 3 "sverse" received signal SIGUSR2, User defined signal 
2.

   Thread 1 "sverse" received signal SIGSEGV, Segmentation fault.
   0x00007ffff7edc200 in ?? ()
   (gdb) backtracfe
   Undefined command: "backtracfe".  Try "help".
   (gdb) backtrace
   #0  0x00007ffff7edc200 in ?? ()
   #1  0x0000555555606242 in object.opEquals(Object, Object) 
(lhs=0x7ffff7edc120, rhs=0x7ffff7edc080)
     at ../../../../src/libphobos/libdruntime/object.d:152
   #2  0x0000555555581fb9 in 
sverse.server.serverpanel.ServerPanel.canMove(sverse.core.entity.Entity) (this=0x7ffff7ede000,
     movedEntity=0x7ffff7edf1c0) at 
./sverse/server/serverpanel.d:129
   #3  0x0000555555581e13 in 
sverse.server.serverpanel.ServerPanel.attemptToApplyMove(sverse.core.entity.Entity, dmath.vector.Vector!(int).Vector) (this=0x7ffff7ede000, entity=0x7ffff7edf1c0, originalPosition=0x7ffff7fd6ec0) at ./sverse/server/serverpanel.d:107
   #4  0x0000555555581afb in 
sverse.server.serverpanel.ServerPanel.update() 
(this=0x7ffff7ede000) at ./sverse/server/serverpanel.d:72
   #5  0x000055555557f971 in 
sverse.server.server.Server.updateAllPanels() 
(this=0x7ffff7eda100) at ./sverse/server/server.d:190
   #6  0x000055555557f15e in sverse.server.server.Server.tick() 
(this=0x7ffff7eda100) at ./sverse/server/server.d:113
   #7  0x000055555557c926 in 
sverse.sverse.runServer(immutable(char)[], ushort) 
(addressString=..., port=6001) at ./sverse/sverse.d:99
   #8  0x000055555557c398 in D main (args=...) at 
./sverse/sverse.d:26