From: Allen Mitchell <ajm@...>
Date: 2003-08-05T08:13:23+09:00
Subject: [BUG] ruby 1.8.0 - GC


Platform: Windowx XP

I have an application using FXRuby (1.0.24).  In this application I have a
left/right split with client records on the left and detail records on the
right.  On a selection change in the left window, I use a thread to populate
the right window with the details.

I am getting a memory access violation while stressing the application with
the use of the up and down arrow keys in the left window. This causes
multiple threads to queue on a mutex to populate the right window.  Without
fail, this results in a memory access violation.  I rebuilt ruby ( VC6 ),
added map and COD files and debugged it thru Dr. Watson.

This analysis always points me to the same line of code in rb_newobj
(gc.c )...

VALUE
rb_newobj()
{
    VALUE obj;

    if (!freelist) rb_gc();

    obj = (VALUE)freelist;
    freelist = freelist->as.free.next;  <----------------------------------
    MEMZERO((void*)obj, RVALUE, 1);
    return obj;
}

I am starting to suspect that there is an error in GC that only manifests
itself in a threaded application under load.

To confirm this, I disabled GC at the start of the app and tried to cause it
to fail.  I could not make it fail... however an application that grew to
300+ MB isn't much use.

I'm going to settle into the C code, but I was just wondering if anyone else
has had an occurance of the same sort of thing.

I have also seen something like this in 1.6.8, but it was very infrequent in
comparison to 1.8.0.

Matz, I can forward logs and map files if they would be of any assistance.

Thanks...