Subject: bug#19180: guile bug#19180: vacuum_weak_hash_table error

From: Anand Mohanadoss <[email-masked]>
Date: Mon, 15 Dec 2014 12:06:44 +0530

Dear Ludovic,

Given your recommendation to use the 'stable-2.0' branch, we tried to
create a fix for the issue with our limited knowledge (assuming that the
size of the hash is getting corrupted by multiple threads).  The process
ran to completion, but, we got different results compared to what we get
with threading disabled.  So, it didn't really help and our assumption
appears to be incorrect. Is there something else we can try, to help you
with creating a proper patch for this issue?

Here is what we changed in hashtab.c -

130a131
>   size_t orig_len = len;
137,138c138,144
<       assert (removed <= len);
<       len -= removed;
---
>       if (removed <= len)
>         len -= removed;
>       else
>       {
>         printf ("Vacuum weak hash table assert Table=%p len=%zi
removed=%zi orig_len=%zi n_items=%zi\n", table, len, removed, orig_len,
SCM_HASHTABLE_N_ITEMS (table));
>         len = 0;
>       }

With this change, we got lines similar to the following printed
periodically -

Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=2 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=2 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=3 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=2 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=4 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=2 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2321
n_items=2321
......
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=205
n_items=205
.......
Vacuum weak hash table assert Table=0x9bdb840 len=1 removed=2 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=2 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274
Vacuum weak hash table assert Table=0x9bdb840 len=0 removed=1 orig_len=2274
n_items=2274

Thanks,
Anand

On Mon, Dec 8, 2014 at 3:04 PM, Ludovic Courtès <[email-masked]> wrote:

> Anand Mohanadoss <[email-masked]> skribis:
>
> > I downloaded the current guile code in git and will give it a try.  But,
> > given that this is not a stable release, I am not sure if we can really
> use
> > it for our purposes.
> >
> > Do you or Ludovic know when a stable 2.2 version will be released?  From
> > stability point of you, would it be better to use a patched version of
> > 2.0.11 that handles the case we noticed (e.g. don't attempt to remove
> items
> > from hash table if len = 0)?
>
> There is not ETA for 2.2.
>
> For now, I would recommend using the ‘stable-2.0’ branch, which
> corresponds to what will (hopefully soon) become 2.0.12.
>
> Thanks,
> Ludo’.
>