JProfiler Get rid of your performance problems and memory leaks! Modern Garbage Collection Tuning Java Performance Training Courses COURSES AVAILABLE NOW. We can provide training courses to handle all your Java performance needs Java Performance Tuning, 2nd ed The classic and most comprehensive book on tuning Java Java Performance Tuning Newsletter Your source of Java performance news. Subscribe now! Enter email: Training online Threading Essentials course JProfiler Get rid of your performance problems and memory leaks!

Back to newsletter 243 contents

https://lkorinth.github.io/posts/2020-11-27-metaspace.html
Metaspace in OpenJDK 16 (Page last updated November 2020, Added 2021-02-25, Author Leo Korinth, Publisher lkorinth). Tips:

• For small class loaders small class loaders huge savings can be made in Metaspace with JDK 16+.
• Metaspace allocates memory outside the Java heap.
• Metaspace can allocate memory within a specified address space, allowing class headers to us 32-bit indexes on 64-bit machines. Related flags are -XX:CompressedClassSpaceSize, -XX:+UseCompressedClassPointers and -XX:+UseCompressedOops.

https://www.morling.dev/blog/talking-to-postgres-through-java-16-unix-domain-socket-channels/
Talking to Postgres Through Java 16 Unix-Domain Socket Channels (Page last updated February 2021, Added 2021-02-25, Author Gunnar Morling, Publisher morling). Tips:

• Unix domain sockets are both more secure and also more efficient than TCP/IP loopback connections.
• A really interesting feature of Unix domain sockets is the ability to transfer open file descriptors from one process to another.

https://inside.java/2021/02/03/jep380-unix-domain-sockets-channels/
JEP-380: Unix domain socket channels (Page last updated February 2021, Added 2021-02-25, Author Michael McMahon, Publisher Inside Java). Tips:

• Unix domain sockets bypasses the TCP/IP stack with consequential improvements in latency and CPU usage.
• Server instance is ServerSocketChannel.open(StandardProtocolFamily.UNIX).bind(UnixDomainSocketAddress.of("/foo/bar.socket")), a client instance SocketChannel.open(StandardProtocolFamily.UNIX).bind(UnixDomainSocketAddress.of("/foo/bar.socket")).
• It is good practice when cleaning up after a Unix domain server socket shuts down to ensure that its socket file gets deleted, as the file is otherwise persisted.

https://nipafx.dev/java-unix-domain-sockets/
Code-First Unix Domain Socket Tutorial (Page last updated March 2021, Added 2021-03-29, Author Nicolai Parlog, Publisher nipafx.dev). Tips:

• Java's socket channel / server-socket channel API can use Unix domain sockets (since Java 16) for faster and more secure inter-process communication on the same host
• The Unix domain socket file needs to have the correct permissions for the program for all instances of the program (ie for all users who launch the program).
• Obtain a UnixDomainSocketAddress (eg using the static of() method), and open using ServerSocketChannel/SocketChannel.open(StandardProtocolFamily.UNIX) then bind() to the address. Finally the server should ServerSocketChannel.accept() and the client should SocketChannel.connect(). The resulting IO is executed the same way as for other sockets.
• Unix domain sockets have faster setup times and higher data throughput than TCP/IP loopback connections. They also have better security (because standard file-based access control is used).

Jack Shirazi Back to newsletter 243 contents