On Tue, 8 Jun 2021 19:26:14 GMT, Brian Burkhalter <b...@openjdk.org> wrote:
>> This PR-*draft* is **work in progress** and an invitation to discuss a >> possible solution for issue >> [JDK-8265891](https://bugs.openjdk.java.net/browse/JDK-8265891). It is *not >> yet* intended for a final review. >> >> As proposed in JDK-8265891, this PR provides an implementation for >> `Channels.newInputStream().transferTo()` which provide superior performance >> compared to the current implementation. The changes are: >> * Prevents transfers through the JVM heap as much as possibly by offloading >> to deeper levels via NIO, hence allowing the operating system to optimize >> the transfer. >> * Using more JRE heap in the fallback case when no NIO is possible (still >> only KiBs, hence mostl ynegligible even on SBCs) to better perform on modern >> hardware / fast I/O devides. >> >> Using JMH I have benchmarked both, the original implementation and this >> implementation, and (depending on the used hardware and use case) >> performance change was approx. doubled performance. So this PoC proofs that >> it makes sense to finalize this work and turn it into an actual OpenJDK >> contribution. >> >> I encourage everybody to discuss this draft: >> * Are there valid arguments for *not* doing this change? >> * Is there a *better* way to improve performance of >> `Channels.newInputStream().transferTo()`? >> * How to go on from here: What is missing to get this ready for an actual >> review? > > src/java.base/share/classes/sun/nio/ch/ChannelOutputStream.java line 113: > >> 111: if ((off < 0) || (off > bs.length) || (len < 0) || >> 112: ((off + len) > bs.length) || ((off + len) < 0)) { >> 113: throw new IndexOutOfBoundsException(); > > Could the bounds checking be done as follows? > > `Objects.checkFromIndexSize(off, len, bs.length);` > > Same comment applies to lines 146 and 219 in `java.nio.channels.Channels`. I'd like to abstain from changes in ChannelOutputStream, as I did not write that code at all. It is simply moved from being an inner class. Please let's concentrate on the code I actually wrote in this PR. Thanks. ------------- PR: https://git.openjdk.java.net/jdk/pull/4263
