Map phase timeout

Christian Dahlqvist christian at
Mon Apr 8 03:14:57 EDT 2013


Without having access to the mapreduce functions you are running, I would assume that a mapreduce job both writing data to disk as well as deleting the written record from Riak might be quite slow. This is not really a use case mapreduce was designed for, and when a mapreduce job crashes or times out it is difficult to know how far along the processing of different records it got. 

I would therefore recommend considering running this type of archiving and delete job as an external batch process instead as it will give you better control over the execution and avoid timeout problems. 

Best regards,


On 8 Apr 2013, at 00:49, Matt Black < at> wrote:

> Dear list, 
> I'm currently getting a timeout during a single phase of a multi-phase map reduce query. Is there anything I can do to assist this in running?
> It's purpose is to backup and remove objects from Riak, so it will run periodically during quiet times moving old data out of Riak into file storage.
> Traceback (most recent call last):
>   File "./tools/", line 185, in <module>
>     main()
>   File "./tools/", line 181, in main
>     args.func(**kwargs)
>   File "/srv/backup/tools/", line 295, in do_map_reduce
>     raise e
> Exception: {"phase":2,"error":"timeout","input":"[<<\"cart-products\">>,<<\"cd67d7f6e2688bc2089e6fa79506ac05-2\">>,{struct,[{<<\"uid\">>,<<\"cd67d7f6e2688bc2089e6fa79506ac05\">>},{<<\"cart\">>,{struct,[{<<\"expired_ts\">>,<<\"2013-03-05T19:12:23.906228\">>},{<<\"last_updated\">>,<<\"2013-03-05T19:12:23.906242\">>},{<<\"tags\">>,{struct,[{<<\"type\">>,<<\"AB\">>}]}},{<<\"completed\">>,false},{<<\"created\">>,<<\"2013-03-04T02:10:18.638413\">>},{<<\"products\">>,[{struct,[{<<\"cost\">>,0},{<<\"bundleName\">>,<<\"Product\">>},...]},...]},...]}},...]}]","type":"exit","stack":"[{riak_kv_w_reduce,'-js_runner/1-fun-0-',3,[{file,\"src/riak_kv_w_reduce.erl\"},{line,283}]},{riak_kv_w_reduce,reduce,3,[{file,\"src/riak_kv_w_reduce.erl\"},{line,206}]},{riak_kv_w_reduce,maybe_reduce,2,[{file,\"src/riak_kv_w_reduce.erl\"},{line,157}]},{riak_pipe_vnode_worker,process_input,3,[{file,\"src/riak_pipe_vnode_worker.erl\"},{line,444}]},{riak_pipe_vnode_worker,wait_for_input,2,[{file,\"src/riak_pipe_vnode_worker.erl\"},{line,376}]},{gen_fsm,handle_msg,7,[{file,\"gen_fsm.erl\"},{line,494}]},{proc_lib,...}]"}
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