TCompactProtocol isn't suitable for reuse in partialDeserialize
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Key: THRIFT-739
URL: https://issues.apache.org/jira/browse/THRIFT-739
Project: Thrift
Issue Type: Bug
Components: Library (Java)
Affects Versions: 0.3
Reporter: Bryan Duxbury
Assignee: Bryan Duxbury
Fix For: 0.3
Took me a bit to track this one down. Recently, I noticed that one of our
applications that uses TDeserializer, TCompactProtocol, and the
partialDeserialize method had a very large number of deserialization errors
popping up. It turns out that when I implemented direct buffer access in a few
spots, I also improved TDeserializer to reuse a single transport and protocol.
However, once the partialDeserialize method gets what it's looking for, it
returns without consuming the rest of the buffer, leaving a bunch of dangling
field id deltas on its internal stack. This causes subsequent
partialDeserialization attempts to fail. Once I got one failure, I'd get a new
TDeserializer, so it looks like about 50% of my deserializations were failing.
There seems to be two separate possible solutions for this problem. The first
is to add a "reset" method to TProtocol that does nothing in most protocols,
but stateful protocols implement so that they can clear themselves out. Then,
TDeserializer calls this all the time. The other alternative is to add a
"isReusable" or "isStateful" method to TProtocol, and just don't reuse those
Protocols that are inappropriate. Personally, I prefer the former solution, but
I'd love to hear others' thoughts.
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