On Mon, May 5, 2014 at 7:35 PM, Boris Zbarsky <bzbar...@mit.edu> wrote:
> On 5/5/14, 7:29 PM, Kenneth Russell wrote: > >> There's no provision in the web worker >> specification for allocation of a web worker to fail gracefully, or >> for a worker to be suspended indefinitely. >> > > This is not actually true. Nothing in the spec requires a UA to expose > the full parallelism of the hardware to workers, so you can just start > queueing them when you hit too many; that's not black-box distinguishable > from limited hardware resources. > > > Even if a worker had its >> priority designated as "low", it would still need to be started. >> > > Sure, in the sense that the caller has to be able to postMessage to it. > > > On 32-bit systems, at least, spawning too many workers will cause the >> user agent to run out of address space fairly quickly. >> > > You're assuming that each worker, as soon as it can accept messages, has a > thread with its own address space dedicated to it. > > While this is one possible implementation strategy, it's not required by > the spec (and e.g. Gecko does not use this implementation strategy). > > > It would be great to design a new parallelism architecture for the >> web, but from a practical standpoint, no progress has been made in >> this area for a number of years, and web developers are hampered today >> by the absence of this information. I think it should be exposed to >> the platform. >> > > Again, note that currently nothing requires a UA to allow an arbitrary > number of workers running at once. Gecko will certainly limit the number > of in-flight workers available to a particular origin, queueing up new ones > until old ones terminate. So navigator.cores on machines with a large > number of cores may not actually be a useful measure, since the UA may not > allow that many workers to be actively on the CPU at once for a given > origin anyway. > This is why this API should return the number of actual parallel tasks that are allowed by the browser. There would be no point if this API would return a number that is larger than that.
