[Issue 6236] New: Subtle bug with Windows timer, hashes and imports

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=6236

           Summary: Subtle bug with Windows timer, hashes and imports
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: andrej.mitrovich at gmail.com


--- Comment #0 from Andrej Mitrovic <andrej.mitrovich at gmail.com> 2011-07-01 16:01:12 PDT ---
!!PLEASE BE CAREFUL!! 

I've tested this on my own system, and it just crashes the app. But I've also
tested it in a VirtualBox on Win7 and it completely froze the system.

This is the smallest test case I could make, you'll have to download it from:
https://github.com/AndrejMitrovic/temporary/tree/master/hashbug

Extract the hashbug folder, build the app with build.bat, and then keep
resizing the window for a few seconds. In just a couple of seconds there's a
crash with:

---------------------------
hashbug.exe - Application Error
---------------------------
The instruction at "0x00403b39" referenced memory at "0x0000000c". The memory
could not be "read".
---------------------------

First of all, it doesn't matter that there's no WinMain function here, WinMain
is just a convention and the bug can be recreated with a WinMain function as
well.

If you comment out "import std.utf;" the bug disappears, even though std.utf is
never used in the module.

If you change the static hash in BugCallback with a globally shared one
"__gshared int[int] hash;" outside the function then the bug seems to go away.

If you replace the line "static int[1] arr = [1];" in BugCallback with "static
int[1] arr = [0];", then the crash only happens when exiting.

If you comment out "hash[arr[0]] = 0;" in BugCallback, the bug disappears.

If you replace that line with "hash[0] = 0;", then the crash only happens when
exiting.

If you comment out the line "foo ~= 1;" in a completely different function
"BugFunction" that runs in another thread, the bug disappears. That function
keeps expanding an array, but it doesn't cause a stackoverflow or anything.

DDBG shows this:

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION(0xc0000005) at __aaGetX
(0x00403b39) thread(2728)

aaGetX looks like a Hash function from Druntime. So my guess is the hash does
something that doesn't work quite well with the Windows timer.

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