user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/sync/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/sync">@sync, which in turn calls wait() for all the futures synchronously. Not only that is slightly detrimental for network operations (latencies add up), but in case of Distributed the call to wait() may actually cause some compilation on remote processes, which is also wait()ed for. In result, some operations took a great amount of "serial" processing time if executed on many workers at once. For me, this closes #44645. The major change can be illustrated as follows: First add some workers: ``` using Distributed addprocs(10) ``` and then trigger something that, for example, causes package imports on the workers: ``` using SomeTinyPackage ``` In my case (importing UnicodePlots on 10 workers), this improves the loading time over 10 workers from ~11s to ~5.5s. This is a far bigger issue when worker count gets high. The time of the processing on each worker is usually around 0.3s, so triggering this problem even on a relatively small cluster (64 workers) causes a really annoying delay, and running `@everywhere` for the first time on reasonable clusters (I tested with 1024 workers, see #44645) usually takes more than 5 minutes. Which sucks. Anyway, on 64 workers this reduces the "first import" time from ~30s to ~6s, and on 1024 workers this seems to reduce the time from over 5 minutes (I didn't bother to measure that precisely now, sorry) to ~11s. Related issues: - Probably fixes #39291. - #42156 is a kinda complementary -- it removes the most painful source of slowness (the 0.3s precompilation on the workers), but the fact that the wait()ing is serial remains a problem if the network latencies are high.

Commits

Commits on Mar 18, 2022

avoid using @sync_add on remotecalls

Commits on Mar 22, 2022

undo the wrapping of remotecall exceptions in TaskFailedException

simplify wait() and fetch() methods for UnwrapTaskFailedException

avoid overusing macros

fix comment english

rename @async_nowrap to more precise @async_unwrap

explicitly import @async_unwrap from Base

avoid using `@sync_add` on remotecalls

rename `@async_nowrap` to more precise `@async_unwrap`

explicitly import `@async_unwrap` from Base