Re: Memory Corruption Issue??

[Bottled Gin via Digitalmars-d]

The fix turned out to be much simpler than what I had thought.

https://github.com/D-Programming-Language/druntime/pull/1506

Re: Memory Corruption Issue??

[Bottled Gin via Digitalmars-d]

Greetings

I am using my D code as a dynamically loadable library that gets 
loaded at run time into C/C++ world. As discussed earlier on this 
thread, the GC does not mark TLS objects in this scenario and as 
a result the GC ends up collecting TLS objects even though these 
objects are still in use. More details of the issue can be found 
on the bug tracker https://issues.dlang.org/show_bug.cgi?id=15513


@Daniel provided two workarounds to this issue. One was to 
disable the GC altogether. I do not want to do that since my 
application generates too much data that necessitates regular 
sweeping.


The other suggested workaround was to explicitly invoke 
GC.addRoot for all the TLS objects. This worked for me for some 
situations, but in other scenarios I am still facing crashes. I 
think these crashes may be resulting from the invisible TLS 
objects in phobos and druntime etc. I have confirmed that all 
these crashes subside if I disable GC altogether and also that 
the crashes do not happen if I make a D bases executable instead 
of DLL.


I want to know if someone is working on this issue. If no one is, 
I am ready to spend time and get this behind me. Actually I have 
already worked on this bug and I think now I have a fair idea of 
what is happening.


Is it the right forum to discuss my findings, or should I put my 
comments on bugzilla. I need some guidance in finding the right 
fix.


Regards
- Puneet

Re: Memory Corruption Issue??

[Bottled Gin via Digitalmars-d]

Thanks Daniel

I have added the testcase to a more obscure testcase that I had 
raised on Bugzilla earlier.

https://issues.dlang.org/show_bug.cgi?id=15513

I want to request developers to show some love.

Regards
- Puneet

Re: Memory Corruption Issue??

[Johannes Pfau via Digitalmars-d]

Am Wed, 20 Jan 2016 09:12:57 +
schrieb Bottled Gin :

> Greetings
> 
> I am struggling with strange memory corruption issues with 
> dmd-2.069.2 release.
> 

Could be GC scanning issues. Can you try disabling the garbage collector
and see if it still crashes?

Re: Memory Corruption Issue??

[Daniel Kozak via Digitalmars-d]

On Wednesday, 20 January 2016 at 09:12:57 UTC, Bottled Gin wrote:

Greetings

I am struggling with strange memory corruption issues with 
dmd-2.069.2 release.


[...]


As a workaround you can mark Hash class as a shared

final shared class Hash

Re: Memory Corruption Issue??

[Daniel Kozak via Digitalmars-d]

On Wednesday, 20 January 2016 at 11:49:29 UTC, Daniel Kozak wrote:
On Wednesday, 20 January 2016 at 09:12:57 UTC, Bottled Gin 
wrote:

Greetings

I am struggling with strange memory corruption issues with 
dmd-2.069.2 release.


...
./main
Start frop from C
0 -> @�+

The last line is the content of an array which is actually 
filled with only dashes in the code.


Kindly help. I want to make sure that I am not making a 
mistake before I file a bug on dlang bugzilla.


Regards
- Puneet


Another workaround is to use GC.addRoot for dynamic allocated 
data in Dynamic.proc


void proc () {
import core.memory: GC;
dash.length = 32;
GC.addRoot(cast(void*)dash.ptr);
dash[] = '-';
}


And another one is hold pointer to data:

class Dynamic {
  static char[] space;
  static char[] dash;
  char* dash_ptr;
  void rehash () {
static Hash hash ;
hash = new Hash;
hash.clear();
  }
  void proc () {
import core.memory: GC;
dash.length = 32;
dash_ptr = dash.ptr;
dash[] = '-';
  }
}

Re: Memory Corruption Issue??

[Daniel Kozak via Digitalmars-d]

On Wednesday, 20 January 2016 at 11:06:53 UTC, Daniel Kozak wrote:
On Wednesday, 20 January 2016 at 09:12:57 UTC, Bottled Gin 
wrote:

Greetings

I am struggling with strange memory corruption issues with 
dmd-2.069.2 release.


[...]


As a workaround you can mark Hash class as a shared

final shared class Hash


But this will change behavour because it will not be in TLS 
anymore

Re: Memory Corruption Issue??

[Daniel Kozak via Digitalmars-d]

On Wednesday, 20 January 2016 at 11:08:46 UTC, Daniel Kozak wrote:
On Wednesday, 20 January 2016 at 11:06:53 UTC, Daniel Kozak 
wrote:
On Wednesday, 20 January 2016 at 09:12:57 UTC, Bottled Gin 
wrote:

Greetings

I am struggling with strange memory corruption issues with 
dmd-2.069.2 release.


[...]


As a workaround you can mark Hash class as a shared

final shared class Hash


But this will change behavour because it will not be in TLS 
anymore


GC.disable seems help

Re: Memory Corruption Issue??

[Daniel Kozak via Digitalmars-d]

On Wednesday, 20 January 2016 at 09:12:57 UTC, Bottled Gin wrote:

Greetings

I am struggling with strange memory corruption issues with 
dmd-2.069.2 release.


...
./main
Start frop from C
0 -> @�+

The last line is the content of an array which is actually 
filled with only dashes in the code.


Kindly help. I want to make sure that I am not making a mistake 
before I file a bug on dlang bugzilla.


Regards
- Puneet


Another workaround is to use GC.addRoot for dynamic allocated 
data in Dynamic.proc


void proc () {
import core.memory: GC;
dash.length = 32;
GC.addRoot(cast(void*)dash.ptr);
dash[] = '-';
}

Re: Memory Corruption Issue??

[Bottled Gin via Digitalmars-d]

Another workaround is to use GC.addRoot for dynamic allocated 
data in Dynamic.proc


void proc () {
import core.memory: GC;
dash.length = 32;
GC.addRoot(cast(void*)dash.ptr);
dash[] = '-';
}


And another one is hold pointer to data:

class Dynamic {
  static char[] space;
  static char[] dash;
  char* dash_ptr;
  void rehash () {
static Hash hash ;
hash = new Hash;
hash.clear();
  }
  void proc () {
import core.memory: GC;
dash.length = 32;
dash_ptr = dash.ptr;
dash[] = '-';
  }
}


Daniel, thanks for confirming the bug and for providing 
workaround. The second workaround (saving the pointer) will not 
work on my real project though. I have multiple threads and the 
TLS variable will have a different pointer on each thread.


Also, can you please tell me how to addRoot an assoc array to GC. 
It seems there is no ptr property available for assoc arrays.


Regards
- Puneet

Re: Memory Corruption Issue??

[Daniel Kozak via Digitalmars-d]

V Wed, 20 Jan 2016 13:58:46 +
Bottled Gin via Digitalmars-d  napsáno:

> >> Another workaround is to use GC.addRoot for dynamic allocated 
> >> data in Dynamic.proc
> >>
> >> void proc () {
> >> import core.memory: GC;
> >> dash.length = 32;
> >> GC.addRoot(cast(void*)dash.ptr);
> >> dash[] = '-';
> >> }  
> >
> > And another one is hold pointer to data:
> >
> > class Dynamic {
> >   static char[] space;
> >   static char[] dash;
> >   char* dash_ptr;
> >   void rehash () {
> > static Hash hash ;
> > hash = new Hash;
> > hash.clear();
> >   }
> >   void proc () {
> > import core.memory: GC;
> > dash.length = 32;
> > dash_ptr = dash.ptr;
> > dash[] = '-';
> >   }
> > }  
> 
> Daniel, thanks for confirming the bug and for providing 
> workaround. The second workaround (saving the pointer) will not 
> work on my real project though. I have multiple threads and the 
> TLS variable will have a different pointer on each thread.
> 
> Also, can you please tell me how to addRoot an assoc array to GC. 
> It seems there is no ptr property available for assoc arrays.
> 
> Regards
> - Puneet
> 
> 
>

You can use cast(void *)aa;

something like this:

class Dynamic {
  static char[] space;
  static char[int] dash;
  void rehash () {
static Hash hash ;
hash = new Hash;
hash.clear();
  }
  void proc () {
import core.memory: GC;
//GC.addRoot(cast(void *)dash); // not here
{
dash[i] = '-';
}
GC.addRoot(cast(void *)dash); // must be after allocation
  }
}


Be careful because you mast use addPtr after aa is initialized (you put
something to it)