jungfrauandClaude Opus 5
a22a51372e
ParallelFor and ParallelChunks started fresh OS threads on every call, one per chunk, through std::async. There are 57 call sites and several sit inside iterative fits, so one run of the heaviest crystal created 13 497 threads and a 900-frame dataset 7 320. Both now run on a persistent pool. The contracts are unchanged: ParallelChunks keeps the same worker count and the same fixed split, so a reduction sums term for term as before, and ParallelFor keeps stealing per item. Two things in the pool are worth knowing. The caller is one of the hands - it claims its own region's tasks and then waits only on tasks already running - so a region entered from inside another region cannot deadlock at any depth, which a shared-queue pool would. And a task wakes one worker rather than the whole pool: on a large machine notify_all wakes every idle thread to find nothing, once per region, tens of thousands of times a run. Two hand-rolled copies of the same pattern now use it, in FrenchWilson and in the two histogram passes of ComputeAsuGroups. Be clear about what this buys today: nothing measurable. Thread creations drop 13 497 -> 770 and entering a parallel region goes from 1.2-2.2 ms to 112 us, an 11-20x cut, but wall clock on 48 threads is level with before, inside the +-5 % this machine's run-to-run placement is worth. What it removes is a cost that grows with the thread count - measured, entry is linear in it - and the machine this is heading for has four times the threads of the one it was measured on, where the same 335 regions a run would cost about 1.8 s of pure thread creation. ComputeAsuGroups' histogram also changes. It is an nthreads x n_groups table, 936 MB at -N 48 on the heaviest crystal and allocated five times a run, and the prefix over it walked DOWN a column - a 19.5 MB stride, so a cache and TLB miss per step, 234 M of them, serially. Both passes now walk rows and split over group ranges. The counts are integers, so the result is bit-identical. This one is reasoning, not measurement: at 48 threads it sits under this machine's noise and could not be shown either way. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Jungfraujoch
Application to receive data from the PSI JUNGFRAU and EIGER detectors.
All documentation is now placed in docs/ subdirectory and for the current version hosted on Jungfraujoch Read The Docs page.