core.exception.InvalidMemoryOperationError

[francesco cattoglio via Digitalmars-d-learn]

On Friday, 11 July 2014 at 11:43:44 UTC, Joakim wrote:
> On Thursday, 10 July 2014 at 15:36:53 UTC, francesco cattoglio 
> wrote:
>> A code I'm working on stops working and starts printing an 
>> infinite loop of
>> core.exception.InvalidMemoryOperationError
>> to the command line output. The code is quite complex and the 
>> bug seems to present itself almost in random situation so I 
>> would like to try to understand the issue better before 
>> looking for the wrong line of code hiding somewhere. I've read 
>> it might be that something is trying to allocate during a 
>> destructor call, but it sounds really strange to me that 
>> there's a neverending amount of exceptions being thrown. This 
>> is the first exception being thrown (nothing is thrown before 
>> the infinite loop begins).
>>
>> Anyone has suggestions/ideas/heard of a similar stuff before?
>
> If you look at the source for the garbage collector, the only 
> place that error is called is if the gc is trying to malloc or 
> execute other memory operations while the collector is running.
>  I ran across this myself because an assert was getting 
> triggered in a destructor.  Since an assert tries to malloc and 
> the destructor is called by the GC, I got an 
> InvalidMemoryOperationError which swallowed up the message from 
> the original assert.
>
> By putting printfs in the code path in druntime, I was able to 
> track it down to that destructor, otherwise I had no idea where 
> the invalid memory error was getting triggered.  You can 
> probably do the same, but you can be sure it's a GC issue, and 
> I would guess tied to allocating in a destructor (unless you 
> happen to be calling InvalidMemoryOperationErrors somewhere in 
> your own code or some library that you're using, which is 
> unlikely).

It's unfortunate that you wrote this only 4 hours ago, because I 
already spent the morning doing more-or-less the same thing, and 
finaly realized what was happening and WHO was allocating during 
a destructor. :o) It's even somewhat told in the docs of 
core.exception module.
What I really don't understand is how the hell was it possible 
that something managed to either recurse or loop to generate an 
infinite WOE (Wall Of Exceptions).