On Wed, 6 May 2026 00:07:33 GMT, Ashay Rane <[email protected]> wrote:
>> Prior to this patch, every HTTP request created a new 16KB buffer for >> encoding the header, which is typically only a few hundred bytes long. >> This increased pressure on the garbage collector when the client created >> lots of requests. This patch instead makes the header encoder reuse the >> buffer that is created during the handling of the first request. >> >> The caveat, however, is that the downstream consumers of the header are >> asynchronous, so the encoder needs to take special care to ensure that >> it doesn't modify or invalidate the buffer after it hands the buffer >> over to the downstream asynchronous pipeline. To resolve this, this >> patch snapshots the buffer data into compact copies sized to the actual >> encoded length. Doing so makes the buffer immediately available for >> reuse via `clear()` and `limit()`. >> >> For typical requests, this reduces per-request allocation from 16KB to >> a few hundred bytes (i.e. the size of the compact copy of the encoded >> headers), with the 16KB encoding buffer allocated once per connection >> instead of once per request. >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > Ashay Rane has updated the pull request incrementally with one additional > commit since the last revision: > > Address PR comments > > 1. Use 'https' scheme with `.loopback()`, similar to other tests. > > 2. Drop reflection to access the connection and the cached header > buffer. Instead add accessor methods to HttpClientImplAccess that > fetch these members and use them in the tests. src/java.net.http/share/classes/jdk/internal/net/http/Http2Connection.java line 1618: > 1616: private ByteBuffer cachedHeaderBuffer; > 1617: > 1618: ByteBuffer getCachedHeaderBuffer() { I think this new method shouldn't be introduced. As far as I can see, it only gets used in a test. The `cachedHeaderBuffer` must be accessed with the `sendLock` held, which is what the `getHeaderBuffer(int size)` method (rightly) asserts. Having this package private getter can introduce issues if other parts of the code start using it in future. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/30931#discussion_r3301961045
