Trying to print floats and doubles from a fiber it fails with a
segfault, while it is possible to do the same in the main thread.
The expected output of the attached code file:
15
15
Done
However I get:
15
segfault
I am using the DMD64 D Compiler v 2.054 on Debian 64
What am I doing wrong, because using to!string() on the floats and
double allows me to print them to std.out.
I however get weird behavior when I try to do math on the floats and
doubles in the fiber, or when I pass them to C-functions.
Kind regards,
Danny
Comment #1 by Danny.Arends — 2011-08-11T06:21:47Z
Tested on other systems: 32bit Debian Squeeze and Win32, this does not happen and I get the expected output of:
15
15
Done
Comment #2 by code — 2011-08-15T21:22:58Z
Can you please post the code.
Comment #3 by Danny.Arends — 2011-08-16T01:02:02Z
Created attachment 1017
Segfault from fiber
The file I forgot to attach
Comment #4 by Danny.Arends — 2011-08-16T01:02:30Z
Sorry forgot to attach the file.
Comment #5 by code — 2011-08-17T09:04:13Z
I can confirm this crash.
The reason though is not strictly a bug.
What you observe is a stack overflow due to big local buffers
in std.format.formatValue and even bigger ones in libc's vfprintf.
Fibers are allocated with a default stack size of one memory page (usually 4096 Bytes), but calling these two function already allocates >3KB stack space.
As a workaround you can increase the stack size in the Fiber constructor. I'm afraid there is no easy solution to determine the smallest possible stack size that is safe for all your code paths. In this example 8K => 'this() { super(&run, 8192); }' will suffice.
martin