Client.set raises "exception: SUCCESS" when behaviors has buffer_requests=True

[hummus]

$ pip freeze | grep pylibmc
pylibmc==1.4.1
$ python -c "import pylibmc; print pylibmc._pylibmc.libmemcached_version"
1.0.18

# run loclahost server, eg docker official
$ docker run -d -p 11211:11211 memcached:1.4.22
$ python -c "import pylibmc; mc = pylibmc.Client(['localhost'], binary=True, behaviors={'buffer_requests':True}); mc.set('foo', 'bar'); print 'foo is ok' "
pylibmc.Error: error 32 from memcached_set: SUCCESS
$ echo $?
1
$ python -c "import pylibmc; mc = pylibmc.Client(['localhost'], binary=True, behaviors={'buffer_requests':True}); print mc.get('foo')"
bar

[lericson]

I made a test case for this in the test suite; however, as it stands, it is sadly not something we can fix on our side of things. It seems to be a bug in libmemcached itself. memcached_set is returning an error status, MEMCACHED_ERRNO, which implies that the process-global errno should be set. That is set to zero though, so there is a contradiction in the libmemcached code.

[henning]

Hi, our team here seem to be running into this, too.
I'm not yet very deep into understanding the thing yet. As it's still open, I assume it persists. Is there anything known if there is a fix (or even a bugreport to track) in libmemcached?

[lericson]

Hello @henning! To my knowledge no, there is no communication with upstream going on about this. It might prove instructive to try to look at what the intended usage of libmemcached is using buffered requests. Perhaps there is some misunderstanding in the way pylibmc interprets this behavior.

Other than that, I'd say just disable the behavior for now.