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https://issues.apache.org/jira/browse/BEAM-1788?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mike Lambert closed BEAM-1788.
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Resolution: Won't Fix
Fix Version/s: Not applicable
Okay, seems that the official answers were discussed in the associated github
thread:
- do not pickle datastore Clients
- rebuild Clients inside the dataflow workers, ideally in start_bundle
- the datastore team may add warnings to help guide users
Going to close this bug now...
> Using google-cloud-datastore in Beam requires re-authentication
> ---------------------------------------------------------------
>
> Key: BEAM-1788
> URL: https://issues.apache.org/jira/browse/BEAM-1788
> Project: Beam
> Issue Type: Improvement
> Components: sdk-py
> Reporter: Mike Lambert
> Assignee: Ahmet Altay
> Priority: Minor
> Labels: datastore, python
> Fix For: Not applicable
>
>
> When I run a pipeline, I believe everything (params, lexically scoped
> variables) must be pickleable for the individual processing stages.
> I have to load a dependent datastore record in one of my processing
> pipelines. (Horribly inefficient, I know, but it's my DB design for now...)
> A {{google.cloud.datastore.Client()}} is not serializable due to the
> {{google.cloud.datastore._http.Connection}} it contains, that is using GRPC:
> {noformat}
> File "lib/apache_beam/transforms/ptransform.py", line 474, in __init__
> self.args = pickler.loads(pickler.dumps(self.args))
> File "lib/apache_beam/internal/pickler.py", line 212, in loads
> return dill.loads(s)
> File "/Users/me/Library/Python/2.7/lib/python/site-packages/dill/dill.py",
> line 277, in loads
> return load(file)
> File "/Users/me/Library/Python/2.7/lib/python/site-packages/dill/dill.py",
> line 266, in load
> obj = pik.load()
> File
> "/usr/local/Cellar/python/2.7.12_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py",
> line 864, in load
> dispatch[key](self)
> File
> "/usr/local/Cellar/python/2.7.12_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py",
> line 1089, in load_newobj
> obj = cls.__new__(cls, *args)
> File "src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi", line 35, in
> grpc._cython.cygrpc.Channel.__cinit__
> (src/python/grpcio/grpc/_cython/cygrpc.c:4022)
> TypeError: __cinit__() takes at least 2 positional arguments (0 given)
> {noformat}
> So instead, constructing a Client inside my pipeline...it appears to be
> jumping through hoops to recreate the Client, in that *each* execution of my
> pipeline is printing:
> {{DEBUG:google_auth_httplib2:Making request: POST
> https://accounts.google.com/o/oauth2/token}}
> I'm sure Google SRE would be very unhappy if I scaled up this mapreduce. :)
> This is a tricky cross-team interaction issue (only occurs for those using
> google-cloud-datastore *and* apache-beam google-dataflow), so not sure the
> proper place to file this. I've cross-posted it at
> https://github.com/GoogleCloudPlatform/google-cloud-python/issues/3191
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