Getting “Application Error: 10” in App Engine Map-

Question

I'm getting errors like this during the reduce step. The MapReduce Overview page reports that all jobs have completed successfully, but half the records that I was trying to write out were not written. What is causing this error, and how can I fix it?:

    ApplicationError: 10 
Traceback (most recent call last):
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1511, in __call__
    rv = self.handle_exception(request, response, e)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1505, in __call__
    rv = self.router.dispatch(request, response)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1253, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1077, in __call__
    return handler.dispatch()
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 547, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 545, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/base_handler.py", line 65, in post
    self.handle()
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/handlers.py", line 181, in handle
    entity, input_reader, ctx, tstate)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/handlers.py", line 298, in process_data
    output_writer.write(output, ctx)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/output_writers.py", line 693, in write
    ctx.get_pool("records_pool").append(str(data))
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/output_writers.py", line 336, in append
    self.flush()
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/output_writers.py", line 371, in flush
    COUNTER_IO_WRITE_BYTES, len(str_buf))(self._ctx)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 297, in __exit__
    self.close()
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 291, in close
    self._make_rpc_call_with_retry('Close', request, response)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 427, in _make_rpc_call_with_retry
    _make_call(method, request, response)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 252, in _make_call
    _raise_app_error(e)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 195, in _raise_app_error
    raise FileNotOpenedError(e)
FileNotOpenedError: ApplicationError: 10

Traceback (most recent call last):
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/main.py", line 105, in main
    util.run_wsgi_app(APP)
  File "/python27_runtime/python27_lib/versions/1/google/appengine/ext/webapp/util.py", line 98, in run_wsgi_app
    run_bare_wsgi_app(add_wsgi_middleware(application))
  File "/python27_runtime/python27_lib/versions/1/google/appengine/ext/webapp/util.py", line 116, in run_bare_wsgi_app
    result = application(env, _start_response)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1519, in __call__
    response = self._internal_error(e)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1511, in __call__
    rv = self.handle_exception(request, response, e)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1505, in __call__
    rv = self.router.dispatch(request, response)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1253, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1077, in __call__
    return handler.dispatch()
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 547, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 545, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/base_handler.py", line 65, in post
    self.handle()
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/handlers.py", line 181, in handle
    entity, input_reader, ctx, tstate)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/handlers.py", line 298, in process_data
    output_writer.write(output, ctx)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/output_writers.py", line 693, in write
    ctx.get_pool("records_pool").append(str(data))
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/output_writers.py", line 336, in append
    self.flush()
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/output_writers.py", line 371, in flush
    COUNTER_IO_WRITE_BYTES, len(str_buf))(self._ctx)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 297, in __exit__
    self.close()
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 291, in close
    self._make_rpc_call_with_retry('Close', request, response)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 427, in _make_rpc_call_with_retry
    _make_call(method, request, response)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 252, in _make_call
    _raise_app_error(e)
  File "/base/data/home/apps/s~getaround3/dont-make-this-default-export-mr.366029363091232181/mapreduce/lib/files/file.py", line 195, in _raise_app_error
    raise FileNotOpenedError(e)
FileNotOpenedError: ApplicationError: 10 

Answer 1

Holding the file open for more than 30 seconds will also result in this error. Try to break the writes into multiple writes.

refer link for deatils https://groups.google.com/forum/#!topic/google-appengine-java/5XBVaVDKvvs

Answer 2

I increased the number of shards which seems to have fixed the problem. Increasing the number of shards reduces the amount of time each slice has to hold a file open which may have been the cause of the problem I had.