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4 天前 回复了 forschers 创建的主题 › Java › JDK21 9 月 19 日 来咯！ |
@arloor
some blocking operations in the JDK do not unmount the virtual thread, and thus block both its carrier and the underlying OS thread.
If a virtual thread performs a blocking operation such as I/O or BlockingQueue.take() while it is pinned, then its carrier and the underlying OS thread are blocked for the duration of the operation. Frequent pinning for long durations can harm the scalability of an application by capturing carriers.
some blocking operations in the JDK do not unmount the virtual thread, and thus block both its carrier and the underlying OS thread.
If a virtual thread performs a blocking operation such as I/O or BlockingQueue.take() while it is pinned, then its carrier and the underlying OS thread are blocked for the duration of the operation. Frequent pinning for long durations can harm the scalability of an application by capturing carriers.
4 天前 回复了 cbdyzj 创建的主题 › Java › Java 21 今日 GA，有虚拟线程（协程） |
4 天前 回复了 cbdyzj 创建的主题 › Java › Java 21 今日 GA，有虚拟线程（协程） |
补充一个，堆大小为 128M：
Time:
2023-09-20 11:13:18
Used: 108,544 kbytes
Committed: 131,072 kbytes
Max: 131,072 kbytes
GC time:
8.149 seconds on ZGC Minor Cycles (384 collections)
0.006 seconds on ZGC Minor Pauses (1,185 collections)
12.133 seconds on ZGC Major Cycles (61 collections)
0.001 seconds on ZGC Major Pauses (279 collections)
Time:
2023-09-20 11:13:18
Used: 108,544 kbytes
Committed: 131,072 kbytes
Max: 131,072 kbytes
GC time:
8.149 seconds on ZGC Minor Cycles (384 collections)
0.006 seconds on ZGC Minor Pauses (1,185 collections)
12.133 seconds on ZGC Major Cycles (61 collections)
0.001 seconds on ZGC Major Pauses (279 collections)
4 天前 回复了 forschers 创建的主题 › Java › JDK21 9 月 19 日 来咯！ |
@voidmnwzp
你说的是这个吧
There are two scenarios in which a virtual thread cannot be unmounted during blocking operations because it is pinned to its carrier:
When it executes code inside a synchronized block or method, or
When it executes a native method or a foreign function.
官方解释：
The scheduler does not compensate for pinning by expanding its parallelism. Instead, avoid frequent and long-lived pinning by revising synchronized blocks or methods that run frequently and guard potentially long I/O operations to use java.util.concurrent.locks.ReentrantLock instead. There is no need to replace synchronized blocks and methods that are used infrequently (e.g., only performed at startup) or that guard in-memory operations. As always, strive to keep locking policies simple and clear.
后续优化：
In a future release we may be able to remove the first limitation above, namely pinning inside synchronized. The second limitation is required for proper interaction with native code.
你说的是这个吧
There are two scenarios in which a virtual thread cannot be unmounted during blocking operations because it is pinned to its carrier:
When it executes code inside a synchronized block or method, or
When it executes a native method or a foreign function.
官方解释：
The scheduler does not compensate for pinning by expanding its parallelism. Instead, avoid frequent and long-lived pinning by revising synchronized blocks or methods that run frequently and guard potentially long I/O operations to use java.util.concurrent.locks.ReentrantLock instead. There is no need to replace synchronized blocks and methods that are used infrequently (e.g., only performed at startup) or that guard in-memory operations. As always, strive to keep locking policies simple and clear.
后续优化：
In a future release we may be able to remove the first limitation above, namely pinning inside synchronized. The second limitation is required for proper interaction with native code.
5 天前 回复了 forschers 创建的主题 › Java › JDK21 9 月 19 日 来咯！ |
@Goooooos
JEP 446 Scoped Values (Preview)
Introduce scoped values, values that may be safely and efficiently shared to methods without using method parameters. They are preferred to thread-local variables, especially when using large numbers of virtual threads. This is a preview API.
JEP 446 Scoped Values (Preview)
Introduce scoped values, values that may be safely and efficiently shared to methods without using method parameters. They are preferred to thread-local variables, especially when using large numbers of virtual threads. This is a preview API.
5 天前 回复了 forschers 创建的主题 › Java › JDK21 9 月 19 日 来咯！ |
@Mirage09 升级到 11 了，据说后面再升级就容易了。
5 天前 回复了 Ayanokouji 创建的主题 › 程序员 › 好奇：每当 jdk 发布新版的时候，那些拿 jdk8 说事的人，是什么心态。 |
这次新版本的新特性还是很值得期待的。虚拟线程和分代 ZGC
5 天前 回复了 cbdyzj 创建的主题 › Java › Java 21 今日 GA，有虚拟线程（协程） |
分代 ZGC 没人关注吗
5 天前 回复了 forschers 创建的主题 › Java › JDK21 9 月 19 日 来咯！ |
@Goooooos https://openjdk.org/jeps/444
irtual threads support thread-local variables (ThreadLocal) and inheritable thread-local variables (InheritableThreadLocal), just like platform threads, so they can run existing code that uses thread locals.
没看到说有优化
irtual threads support thread-local variables (ThreadLocal) and inheritable thread-local variables (InheritableThreadLocal), just like platform threads, so they can run existing code that uses thread locals.
没看到说有优化
5 天前 回复了 forschers 创建的主题 › Java › JDK21 9 月 19 日 来咯！ |
我看到油管的信息，分代 ZGC 吞吐量是 ZGC 的四倍，堆大小是 ZGC 的五分之一，很期待。
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