RFR(S): 8242848: Improve performance of InflaterOutputStream.write()

[Claes Redestad]

Hi Volker,

On 2020-04-15 19:48, Volker Simonis wrote:
> While doing this change, I've also realized that all the streams in
> java.util.zip (i.e. DeflaterInputStream, GZIPInputStream,
> GZIPOutputStream, InflaterInputStream, DeflaterOutputStream) use an
> internal byte buffer of 512 bytes by default. Looking at the benchmark
> attached to JDK-8242864, I think that increasing this default to a
> bigger size (e.g. 4096 bytes) will considerably speed up (up to 50%)
> read and write operations on these streams when they are created with
> the default buffer size. I think the value "512" is a legacy of old
> times when memory was more precious:)  so  I've opened "JDK-8242864:
> Increase the default, internal buffer size of the Streams in
> java.util.zip" to track that as as separate issue. Do you think it
> makes sense to increase that default value?

Seems reasonable. 8192 seems to be the buffer size we've been converging
on elsewhere (see InputStream, BufferedInputStream, Files, ..). I also
found an instance of 8096, which is either a typo or a clever
optimization to keep the array + array object header fit snugly within
8Kb. You chose. :-)

> 
> Thank you and best regards,
> Volker
> 
> PS: do you think it makes sense to contribute the benchmark attached
> to JDK-8242864 to the code-tools/mh-jdk-microbenchmarks [1] project?
> 
> [1]http://openjdk.java.net/projects/code-tools/jmh-jdk-microbenchmarks/

I'd definitely welcome the micro as part of the patch under
test/micro/org/openjdk/bench/java/util/zip - additionally contributing
to jmh-jdk-microbenchmarks could enable you to test the micro on 8 or
11.

/Claes