6 ms·

The question is not why, but when. When? Our server has long waiting http handlers, which occupy java threads while waiting, thus limiting the server throughpu

The question is not why, but when. When? Our server has long waiting http handlers, which occupy java threads while waiting, thus limiting the server throughput to the number of threads java can maintain, and I'm holding off a rewrite on async servlets for several years already to avoid complicating the code, because I hope cheap threads (fibers) will become available, but there is no timeline for Loom. When can we hope it will be released?

digaozao 7y ago
Maybe with kotlin coroutines you can rewrite the application partially. Is there a difference between that and fibers?
- avodonosov 7y ago
  Kotlin coroutines, as well as js and c# async/await, require us to change declaration of calling function. We can call a "suspend" function only from a "suspend" function, which in turn can only be called by another "suspend" function. So if I change some of my functions to "suspend" everyone upper in the call stack should be changed to "suspend", which is not always possible because that may be a 3rd party code. That's not necesserily a deal breaker, but that's the difference. For Java there is Quasar lib, which introduces async/await through bytecode instrumentation. It's by the same authors who work on the project Loom currently. I don't use it because: a) the project web site feels a bit abandoned; I guess they concentrate on Loom now 2) I need analogues of wait/notify, sychronized, etc which are used in this code and not provided by Quasar; Quasar only provides lower-level primitives. One either need to implement such constructs on top of Quasar, or reimplement the logic. So it's not a drop-in replacement. The project Loom aims to be mostly a drop-in, in particular fibers will support synchronized, wait/notify, etc.
  - deleted 7y ago
    [deleted]
  - jarym 7y ago
    Quasar was created by the same guy (Ron Pressler) that is the tech lead for Project Loom. The reason Quasar feels a bit abandoned is because he's bringing the thinking right into the JVM.
pron 7y ago
As OpenJDK has switched to time-based releases, we no longer plan releases based on features. When a feature is ready, it is merged into the mainline and released in the following release. We never commit to a timeline, but I would say that the probability for fibers to land in one of the two releases next year as quite high. Of course, we release projects gradually, and it's possible that some planned fiber features will not land in the first release, or that the performance in the first release will later be improved etc. However, early access Loom binaries (with API still very much in flux) are expected in a month or so, with the intention of gathering feedback on the API. The decision on when fibers are ready to be merged will greatly depend on that feedback.

digaozao 7y ago

Maybe with kotlin coroutines you can rewrite the application partially. Is there a difference between that and fibers?

avodonosov 7y ago
Kotlin coroutines, as well as js and c# async/await, require us to change declaration of calling function. We can call a "suspend" function only from a "suspend" function, which in turn can only be called by another "suspend" function. So if I change some of my functions to "suspend" everyone upper in the call stack should be changed to "suspend", which is not always possible because that may be a 3rd party code. That's not necesserily a deal breaker, but that's the difference. For Java there is Quasar lib, which introduces async/await through bytecode instrumentation. It's by the same authors who work on the project Loom currently. I don't use it because: a) the project web site feels a bit abandoned; I guess they concentrate on Loom now 2) I need analogues of wait/notify, sychronized, etc which are used in this code and not provided by Quasar; Quasar only provides lower-level primitives. One either need to implement such constructs on top of Quasar, or reimplement the logic. So it's not a drop-in replacement. The project Loom aims to be mostly a drop-in, in particular fibers will support synchronized, wait/notify, etc.
- deleted 7y ago
  [deleted]
- jarym 7y ago
  Quasar was created by the same guy (Ron Pressler) that is the tech lead for Project Loom. The reason Quasar feels a bit abandoned is because he's bringing the thinking right into the JVM.

pron 7y ago

As OpenJDK has switched to time-based releases, we no longer plan releases based on features. When a feature is ready, it is merged into the mainline and released in the following release. We never commit to a timeline, but I would say that the probability for fibers to land in one of the two releases next year as quite high. Of course, we release projects gradually, and it's possible that some planned fiber features will not land in the first release, or that the performance in the first release will later be improved etc. However, early access Loom binaries (with API still very much in flux) are expected in a month or so, with the intention of gathering feedback on the API. The decision on when fibers are ready to be merged will greatly depend on that feedback.