The G1 GC proposal is intended to improve application throughput and latency when using the G1 garbage collector by reducing the amount of synchronization required between application threads and GC threads. Goals include reducing the G1 garbage collector’s synchronization overhead, reducing the size of the injected code for G1’s write barriers, and maintaining the overall architecture of G1, with no changes to user interaction.
The G1 GC proposal notes that although G1, which is the default garbage collector of the HotSpot JVM, is designed to balance latency and throughput, achieving this balance sometimes impacts application performance adversely compared to throughput-oriented garbage collectors such as the Parallel and Serial collectors:
Relative to Parallel, G1 performs more of its work concurrently with the application, reducing the duration of GC pauses and thus improving latency. Unavoidably, this means that application threads must share the CPU with GC threads, and coordinate with them. This synchronization both lowers throughput and increases latency.
The HTTP/3 proposal calls for allowing Java libraries and applications to interact with HTTP/3 servers with minimal code changes. Goals include updating the HTTP Client API to send and receive HTTP/3 requests and responses; requiring only minor changes to the HTTP Client API and Java application code; and allowing developers to opt in to HTTP/3 as opposed to changing the default protocol version from HTTP/2 to HTTP/3.
