This patch introduces the concept of error codes for errors that are
recorded in Impala and are going to be presented to the client. These
error codes are used to aggregate and group incoming error / warning
messages to reduce the spill on the shell and increase the usefulness of
the messages. By splitting the message string from the implementation,
it becomes possible to edit the string independently of the code and
pave the way for internationalization.
Error messages are defined as a combination of an enum value and a
string. Both are defined in the Error.thrift file that is automatically
generated using the script in common/thrift/generate_error_codes.py. The
goal of the script is to have a central understandable repository of
error messages. Adding new messages to this file will require rebuilding
the thrift part. The proxy class ErrorMessage is responsible to
represent an error and capture the parameters that are used to format
the error message string.
When error messages are recorded they are recorded based on the
following algorithm:
- If an error message is of type GENERAL, do not aggregate this message
and simply add it to the total number of messages
- If an error messages is of specific type, record the first error
message as a sample and for all other occurrences increment the count.
- The coordinator will merge all error messages except the ones of type
GENERAL and display a count.
For example, in the case of the parquet file spanning multiple blocks
the output will look like:
Parquet files should not be split into multiple hdfs-blocks.
file=hdfs://localhost:20500/fid.parq (1 of 321 similar)
All messages are always logged to VLOG. In the coordinator error
messages are merged across all backends to retain readability in the
case of large clusters.
The current version of this patch adds these new error codes to some of
the most important error messages as a reference implementation.
Change-Id: I1f1811631836d2dd6048035ad33f7194fb71d6b8
Reviewed-on: http://gerrit.cloudera.org:8080/39
Reviewed-by: Martin Grund <mgrund@cloudera.com>
Tested-by: Internal Jenkins
