On 1/31/14 10:46 AM, Chris Hegarty wrote:
I think your patch can be split into two logical, independent, parts. The
first is the use of unsafe to access the String UTF length. The seconds is
to reuse, where possible, the existing StringBuilder instances, skipping of
primitive/object reading/writing where applicable, and general cleanup.
Since this is a very sensitive area I would like to consider these
separately. To that end, I have taken the changes that are applicable to the
latter, removed any subjective stylistic changes, and made some additional
cleanup improvements.
http://cr.openjdk.java.net/~chegar/serial_stupp.00/webrev/
I agree with splitting the Unsafe usages so they can be reviewed separately. New
and changed usage of Unsafe will require exacting scrutiny.
In general, the cleanups and refactorings look fine.
I have a question about the change to reuse StringBuilder instances. This
replaces freshly allocated StringBuilders stored in local variables with reuse
of a StringBuilder stored in a field of BlockDataInputStream, which in turn is
stored in a field of ObjectInputStream. Thus, instead of creating of lots of
temporaries that become gc-eligible very quickly, this creates a single
long-lived object whose size is the high-water mark of the longest string that's
been read. The change does reduce allocation pressure, but the point of
generational GC is to make allocation and collection of temporaries quite
inexpensive. Is this the right tradeoff?
s'marks
