Wall-time/all tasks profiler (#55889)#193
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d-netto merged 1 commit intov1.10.2+RAIfrom Oct 29, 2024
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One limitation of sampling CPU/thread profiles, as is currently done in Julia, is that they primarily capture samples from CPU-intensive tasks. If many tasks are performing IO or contending for concurrency primitives like semaphores, these tasks won’t appear in the profile, as they aren't scheduled on OS threads sampled by the profiler. A wall-time profiler, like the one implemented in this PR, samples tasks regardless of OS thread scheduling. This enables profiling of IO-heavy tasks and detecting areas of heavy contention in the system. Co-developed with @nickrobinson251.
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NHDaly
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Please run the tests on the branch locally, since we still don't have CI set up here yet. 😭
Otherwise, LGTM! :)
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Tests are passing: julia> Base.runtests(["Profile"])
Running parallel tests with:
nworkers() = 1
nthreads() = 1
Sys.CPU_THREADS = 4
Sys.total_memory() = 64.000 GiB
Sys.free_memory() = 34.233 GiB
Test (Worker) | Time (s) | GC (s) | GC % | Alloc (MB) | RSS (MB)
Profile (1) | started at 2024-10-29T16:18:42.098
Profile (1) | 39.26 | 0.30 | 0.8 | 1768.34 | 1677.02
Test Summary: | Pass Total Time
Overall | 17973 17973 39.9s
SUCCESSand: julia> using Profile
julia> Profile.@profile_walltime sleep(1)
julia> Profile.print()
Overhead ╎ [+additional indent] Count File:Line; Function
=========================================================
╎123 @REPL/src/REPL.jl:386; (::REPL.var"#62#68"{REPL.LineEditREPL, REPL.REPLBackendRef})()
╎ 123 …ulia-RAI/usr/lib/julia/sys.dylib:?; run_frontend(repl::REPL.LineEditREPL, backend::REPL.REPLB…
╎ 123 …ulia-RAI/usr/lib/julia/sys.dylib:?; run_interface(terminal::REPL.Terminals.TextTerminal, m::…
╎ 123 …lia-RAI/usr/lib/julia/sys.dylib:?; (::REPL.var"#do_respond#80"{Bool, Bool, REPL.var"#93#103…
╎ 123 …lia-RAI/usr/lib/julia/sys.dylib:?; eval_with_backend(ast::Any, backend::REPL.REPLBackendRe…
╎ 123 …lia-RAI/usr/lib/julia/sys.dylib:?; take_buffered(c::Channel{Any})
╎ ╎ 123 …ia-RAI/usr/lib/julia/sys.dylib:?; wait(c::Base.GenericCondition{ReentrantLock}; first::B…
╎ ╎ 123 @Base/task.jl:995; wait()
123╎ ╎ 123 …a-RAI/usr/lib/julia/sys.dylib:?; try_yieldto(undo::typeof(Base.ensure_rescheduled))
Total snapshots: 769 |
nickrobinson251
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One limitation of sampling CPU/thread profiles, as is currently done in Julia, is that they primarily capture samples from CPU-intensive tasks. If many tasks are performing IO or contending for concurrency primitives like semaphores, these tasks won’t appear in the profile, as they aren't scheduled on OS threads sampled by the profiler. A wall-time profiler, like the one implemented in this PR, samples tasks regardless of OS thread scheduling. This enables profiling of IO-heavy tasks and detecting areas of heavy contention in the system. Co-developed with @nickrobinson251.
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Apr 4, 2026
Stdlib: Tar URL: https://github.com/JuliaIO/Tar.jl.git Stdlib branch: master Julia branch: master Old commit: e15495e New commit: 6a61f5c Julia version: 1.14.0-DEV Tar version: 1.10.0 (Does not match) Bump invoked by: @DilumAluthge Powered by: [BumpStdlibs.jl](https://github.com/JuliaLang/BumpStdlibs.jl) Diff: JuliaIO/Tar.jl@e15495e...6a61f5c ``` $ git log --oneline e15495e..6a61f5c 6a61f5c Bump codecov/codecov-action from 4 to 6 (#181) 1a1b323 Bump julia-actions/cache from 2 to 3 (#193) ``` Co-authored-by: DilumAluthge <5619885+DilumAluthge@users.noreply.github.com>
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PR Description
Backports JuliaLang#55889.
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