Re: jsonpath

On 11/6/18 4:48 PM, Tomas Vondra wrote:
> On 11/6/18 3:31 PM, Nikita Glukhov wrote:
>> On 29.10.2018 2:20, Tomas Vondra wrote:>
>>
>> ...
>>>
>>> 9) It's generally a good idea to make the individual pieces committable
>>> separately, but that means e.g. the regression tests have to pass after
>>> each patch. At the moment that does not seem to be the case for 0002,
>>> see the attached file. I'm running with -DRANDOMIZE_ALLOCATED_MEMORY,
>>> not sure if that's related.
>>
>> This should definitely be a bug in json support, but I can't reproduce
>> it simply by defining -DRANDOMIZE_ALLOCATED_MEMORY.  Could you provide
>> a stack trace at least?
>>
> I'll try.
> 

Not sure why you can't reproduce the failures, it's perfectly
reproducible for me. For the record, I'm doing this:

./configure --prefix=/home/user/pg-jsonpath --enable-debug
--enable-cassert CFLAGS="-O0 -DRANDOMIZE_ALLOCATED_MEMORY" && make -s
clean && make -s -j4 && make check

After sticking Assert(false) to JsonEncodeJsonbValue (to the default
case), I get a failure like this:

  select json '{}' @* 'lax $[0]';
! WARNING:  unknown jsonb value type: 20938064
! server closed the connection unexpectedly
!     This probably means the server terminated abnormally
!     before or while processing the request.
! connection to server was lost

The backtrace is attached. My guess is JsonValueListGetList in
jsonb_jsonpath_query only does shallow copy instead of copying the
pieces into funcctx->multi_call_memory_ctx, so it gets corrupted on
subsequent calls.

I also attach valgrind report, but I suppose the reported issues are a
consequence of the same bug.

regard

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
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