[Issue 22238] New: Intermittent failure in druntime forkgc2 test

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22238

          Issue ID: 22238
           Summary: Intermittent failure in druntime forkgc2 test
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Mac OS X
            Status: NEW
          Severity: normal
          Priority: P1
         Component: druntime
          Assignee: nobody at puremagic.com
          Reporter: snarwin+bugzilla at gmail.com

druntime's `forkgc2` test sometimes fails, with the following error:

---
forkgc2(91895,0x700000104000) malloc: *** error for object 0x7fe3c3403130:
double free
---

This was recently observed to occur in an auto-tester job running on 64-bit Mac
OS X for Phobos PR 8208 [1]. Re-running the tests caused the error to vanish.

It is possible that this error has a similar cause to the one described in
issue 22222, since the way `fork` and `exit` are used in `forkgc2` is very
similar to the problematic usage pattern described in that issue.

[1] https://github.com/dlang/phobos/pull/8208

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