ValueError: need more than 3 values to unpack on HashQueueTests.test_called_back_error

[Natalia Bidart]

Trace is:

  HashQueueTests
    test_being_hashed ... [OK]
    test_called_back_error ... Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "/home/nessita/canonical/client/trunk/ubuntuone/syncdaemon/hash_queue.py", line 125, in run
    hashdata, crc, size, stat = result
ValueError: need more than 3 values to unpack

                                            [OK]

The test pass the same since the error happens inside a thread.

[Alejandro J. Cura (alecu)]

I'm unable to reproduce this issue, so it's probably fixed by now.

[Natalia Bidart (nataliabidart)]

Hola alecu,

this is still an issue in my env, very likely a timing issue.

[Natalia Bidart (nataliabidart)]

Applying a dummy patch that will have a try-except around the hashdata, crc, size, stat = result code:

=== modified file 'ubuntuone/syncdaemon/hash_queue.py'
--- ubuntuone/syncdaemon/hash_queue.py 2011-10-14 20:02:23 +0000
+++ ubuntuone/syncdaemon/hash_queue.py 2012-03-23 20:43:33 +0000
@@ -122,7 +122,11 @@
             except StopHashing, e:
                 self.logger.debug(str(e))
             else:
- hashdata, crc, size, stat = result
+ try:
+ hashdata, crc, size, stat = result
+ except:
+ print '\n\n\n\n======= RESULT', repr(result)
+ raise
                 self.logger.debug("Hasher: path hash pushed: path=%r hash=%s"
                                   " crc=%s size=%d st_ino=%d st_size=%d"
                                   " st_mtime=%r", path, hashdata, crc, size,

Running that in an infinite loop, I got this:

  HashQueueTests
    test_being_hashed ...

======= RESULT 'foo'
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/home/nessita/canonical/client/trunk/ubuntuone/syncdaemon/hash_queue.py", line 126, in run
    hashdata, crc, size, stat = result
ValueError: need more than 3 values to unpack

                                                 [OK]
    test_called_back_error ... [OK]

[Natalia Bidart (nataliabidart)]

I guess I found the problem: if you open test_hashqueue.py, you will find this piece:

    588 original_hash = hash_queue._Hasher._hash
    589
    590 def f(*a):
    591 """Fake _hash."""
    592 event.wait()
    593 return "foo"
    594 hash_queue._Hasher._hash = f

    588 original_hash = hash_queue._Hasher._hash
    589
    590 def f(*a):
    591 """Fake _hash."""
    592 event.wait()
    593 return "foo"
    594 hash_queue._Hasher._hash = f

(in several places, could please improve all of them?)