[tahoe-dev] Question about changing k/N

[David-Sarah Hopwood]

On 04/06/12 05:48, Kyle Markley wrote:
> Zooko,
> 
> As I went about gathering information to submit a ticket, I discovered something
> interesting.  This probably has something to do with the health of the target
> directories.  I discovered one 2/4 directory that works cleanly, and another 2/4 directory
> that gives an error (after *successfully* creating the link).  I haven't created a ticket
> yet because I'm not sure what's supposed to happen here.  :)
[...]
> My error looks something like this.  The exact message has changed; it used to say there
> was an UncoordinatedWriteError, but my experimentation seems to have changed things a bit,
> and right now I only see that error mentioned in the incident report.
> 
> $ tahoe ln foo: share:foo
> Error: 500 Internal Server Error
> "Traceback (most recent call last):\x0a  File
> \"/usr/local/lib/python2.7/site-packages/twisted/internet/base.py\", line 800, in
> runUntilCurrent\x0a    call.func(*call.args, **call.kw)\x0a  File
> \"/usr/local/lib/python2.7/site-packages/foolscap-0.6.3-py2.7.egg/foolscap/eventual.py\",
> line 26, in _turn\x0a    cb(*args, **kwargs)\x0a  File
> \"/usr/local/lib/python2.7/site-packages/twisted/internet/defer.py\", line 368, in
> callback\x0a    self._startRunCallbacks(result)\x0a  File
> \"/usr/local/lib/python2.7/site-packages/twisted/internet/defer.py\", line 464, in
> _startRunCallbacks\x0a    self._runCallbacks()\x0a--- <exception caught here> ---\x0a 
> File \"/usr/local/lib/python2.7/site-packages/twisted/internet/defer.py\", line 551, in
> _runCallbacks\x0a    current.result = callback(current.result, *args, **kw)\x0a  File
> \"/usr/local/lib/python2.7/site-packages/allmydata/mutable/filenode.py\", line 855, in
> <lambda>\x0a    self._modify_once(modifier, first_time))\x0a  File
> \"/usr/local/lib/python2.7/site-packages/allmydata/mutable/filenode.py\", line 881, in
> _modify_once\x0a    d = self._try_to_download_data()\x0a  File
> \"/usr/local/lib/python2.7/site-packages/allmydata/mutable/filenode.py\", line 959, in
> _try_to_download_data\x0a    d = self._read(c, fetch_privkey=True)\x0a  File
> \"/usr/local/lib/python2.7/site-packages/allmydata/mutable/filenode.py\", line 980, in
> _read\x0a    d = r.download(consumer, offset, size)\x0a  File
> \"/usr/local/lib/python2.7/site-packages/allmydata/mutable/retrieve.py\", line 237, in
> download\x0a    self._setup_download()\x0a  File
> \"/usr/local/lib/python2.7/site-packages/allmydata/mutable/retrieve.py\", line 277, in
> _setup_download\x0a    shares = versionmap[self.verinfo]\x0aexceptions.KeyError: (57,
> '\\x16i\\xdb\\xa8\\xbc\\xd7\\xabrY\\xcdpv\\xa4I\\x82\\xfe\\xa5i\\xed\\x82;\\xca\\xe8\\xcaL\\xf7\\xdav\\xa9\\xf2O\\t',
> '\\x19f_S!&\\xb0\\xa1\\xeb\\x94\\x81F)\\xbb\\x89q', 336, 335, 2, 4,
> '\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x009\\x16i\\xdb\\xa8\\xbc\\xd7\\xabrY\\xcdpv\\xa4I\\x82\\xfe\\xa5i\\xed\\x82;\\xca\\xe8\\xcaL\\xf7\\xdav\\xa9\\xf2O\\t\\x19f_S!&\\xb0\\xa1\\xeb\\x94\\x81F)\\xbb\\x89q\\x02\\x04\\x00\\x00\\x00\\x00\\x00\\x00\\x01P\\x00\\x00\\x00\\x00\\x00\\x00\\x01O',
> (('enc_privkey', 923), ('EOF', 2138), ('share_data', 755), ('signature', 399),
> ('block_hash_tree', 723), ('share_hash_chain', 655)))\x0a"

That looks like https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1670 (I think that bug can
produce either an UncoordinatedWriteError or a KeyError).

-- 
David-Sarah Hopwood ⚥

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