Not a concurrency professional, but my first impression is whether to yield or spin depends on how costly the task you are waiting is - I know yield involves a context switch and can be problematic for small waits.
In addition, in Java, many blocking happens in a way users cannot control - for example, class initialization. Those might be bigger bottlenecks compared to the explicit busy waits. Chen Get Outlook for Android<https://aka.ms/AAb9ysg> ________________________________ From: core-libs-dev <core-libs-dev-r...@openjdk.org> on behalf of Markus KARG <mar...@headcrashing.eu> Sent: Sunday, June 15, 2025 11:49:52 AM To: Archie Cobbs <archie.co...@gmail.com> Cc: core-libs-dev <core-libs-dev@openjdk.org> Subject: Re: Best Practice for Busy Waiting in Java Seems you misunderstood my question. It was *not* what is best to do. It was: "Does the core-libs team have a common-sense / best practice for busy-wait.". The latter is a clear and concise question, and the answer could be as simple as "yes" or "no". Am 15.06.2025 um 18:40 schrieb Archie Cobbs: Just MHO... This is kind of like asking "What's the best way to waste electricity?" It's a nebulous question until you specify what "best" means in this odd scenario.... -Archie On Sun, Jun 15, 2025 at 11:09 AM Markus KARG <mar...@headcrashing.eu<mailto:mar...@headcrashing.eu>> wrote: Recently I was asked by a programmer, what to do if there simply is no other way than actually busy-wait. I see several options: * Do nothing: Costs valuable CPU time and increases carbon footprint. * Do a power-nap: Thread.sleep(1) * Be fair: Thread.yield() gives other threads a chance to execute in this time slot. * Be eco-friendly: Thread.onSpinWait() could reduce carbon footprint. * A combination of that, like "Thread.yield(); Thread.onSpinWait();" As all of that has its pros and cons, and as all of that works differently on each hardware platform, I do wonder if there is some common sense / best practice for busy wait (other than "Replace it using async") in the core-libs team? Thanks! -Markus -- Archie L. Cobbs
