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https://issues.apache.org/jira/browse/HIVE-15491?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mithun Radhakrishnan reassigned HIVE-15491:
-------------------------------------------
Assignee: Mithun Radhakrishnan
> Failures are masked/swallowed in GenericUDTFJSONTuple::process().
> -----------------------------------------------------------------
>
> Key: HIVE-15491
> URL: https://issues.apache.org/jira/browse/HIVE-15491
> Project: Hive
> Issue Type: Bug
> Affects Versions: 2.1.1
> Reporter: Mithun Radhakrishnan
> Assignee: Mithun Radhakrishnan
> Attachments: HIVE-15491.patch
>
>
> I draw your attention to the following piece of code in
> {{GenericUDTFJSONTuple::process()}}:
> {code:java}
> @Override
> public void process(Object[] o) throws HiveException {
> ...
> for (int i = 0; i < numCols; ++i) {
> if (retCols[i] == null) {
> retCols[i] = cols[i]; // use the object pool rather than creating a
> new object
> }
> Object extractObject = ((Map<String, Object>)jsonObj).get(paths[i]);
> if (extractObject instanceof Map || extractObject instanceof List) {
> retCols[i].set(MAPPER.writeValueAsString(extractObject));
> } else if (extractObject != null) {
> retCols[i].set(extractObject.toString());
> } else {
> retCols[i] = null;
> }
> }
> forward(retCols);
> return;
> } catch (Throwable e) { <================= Yikes.
> LOG.error("JSON parsing/evaluation exception" + e);
> forward(nullCols);
> }
> }
> {code}
> The error-handling here seems suspect. Judging from the error message, the
> intention here seems to be to catch JSON-specific errors arising from
> {{MAPPER.readValue()}} and {{MAPPER.writeValueAsString()}}. By catching
> {{Throwable}}, this code masks the errors that arise from the call to
> {{forward(retCols)}}.
> I just ran into this in production. A user with a nearly exhausted HDFS quota
> attempted to use {{json_tuple}} to extract fields from json strings in his
> data. The data turned out to have large record counts and the query used over
> 25K mappers. Every task failed to create a {{RecordWriter}}, thanks to the
> exhausted quota. But the thrown exception was swallowed in the code above.
> {{process()}} ignored the failure for the record and proceeded to the next
> one. Eventually, this resulted in DDoS-ing the name-node.
> I'll have a patch for this shortly.
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