[Openmcl-devel] armcl memory bug 1257 and v1.12-dev.4-3-gdd5622e9 [threading problem?]

[R. Matthew Emerson]

> On Jan 11, 2019, at 3:34 PM, JTK <jetmonk at gmail.com> wrote:
> 
> 
> 
> Apologies for these piece-wise emails.
> 
> I tried to replicate armcl threading problems described in
> https://trac.clozure.com/ccl/ticket/1257 <https://trac.clozure.com/ccl/ticket/1257> 
> and I think I might have found some other issues, as well as a clue to a possible cause
> 
> See https://pastebin.com/2x3mcHMc <https://pastebin.com/2x3mcHMc>
> 
> I found that 
> 
> * a simple thread test with a bit of garbage generation in threads fails with Unhandled Exception 4 on armcl 1.12-dev (v1.12-dev.4-3-gdd5622e9), but does not fail in release version v1.11.5 
> 
> * If I put a lock around the garbage generation (just a make-string), to exercise locking in threads, in v1.11.5 it fails with 	“Current process #<PROCESS Reader 4(26) [Active] #x150D335E> does not own lock #<RECURSIVE-LOCK "glock" [ptr @ #x76105C60] #x150BB0D6> in CCL::%UNLOCK-RECURSIVE-LOCK-OBJECT"
> 
> Is it possible that imperfect locking (race condition?  non atomicity?) in the armcl implementation causes bug 1257, mimicking a GC bug?  

The last time I tried hard to find this bug I utterly failed to find it.

I pasted your comments into the Trac ticket (and I'll be to copying the whole issue over to GitHub soon).

-m



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