Ignore IJulia heartbeat thread

src/pinning.jl

@@ -94,7 +94,7 @@ function pinthreads end
 function _nthreadsarg(threadpool)
     @static if VERSION >= v"1.9-"
         if threadpool == :all
-            return Threads.maxthreadid()
+            return Threads.nthreads(:default) + Threads.nthreads(:interactive)
         else
             return Threads.nthreads(threadpool)
         end
@@ -112,17 +112,8 @@ function pinthreads(cpuids::AbstractVector{<:Integer};
     if force || first_pin_attempt()
         warn && _check_environment()
         _check_cpuids(cpuids)
+        tids = threadids(threadpool)
         limit = min(length(cpuids), nthreads)
-        @static if VERSION >= v"1.9-"
-            if threadpool == :all
-                tids = 1:Threads.maxthreadid()
-            else
-                tids = filter(i -> Threads.threadpool(i) == threadpool,
-                              1:Threads.maxthreadid())
-            end
-        else
-            tids = 1:limit
-        end
         @debug("pinthreads", limit, nthreads, tids)
         for (i, tid) in pairs(@view(tids[1:limit]))
             pinthread(tid, cpuids[i]; warn = false)

src/querying.jl

@@ -19,21 +19,14 @@ See `getcpuid` for more information.
 """
 function getcpuids(; threadpool = :default)::Vector{Int}
     @static if VERSION >= v"1.9-"
-        if threadpool == :all
-            nt = Threads.maxthreadid()
-            tids_pool = 1:nt
-            @assert nt == Threads.nthreads(:default) + Threads.nthreads(:interactive)
-        elseif threadpool in (:default, :interactive)
-            nt = nthreads(threadpool)
-            tids_pool = filter(i -> Threads.threadpool(i) == threadpool,
-                               1:Threads.maxthreadid())
-        else
+        if !(threadpool in (:all, :default, :interactive))
             throw(ArgumentError("Unknown value for `threadpool` keyword argument. " *
                                 "Supported values are `:all`, `:default`, and " *
                                 "`:interactive`."))
         end
+        tids_pool = threadids(threadpool)
+        nt = length(tids_pool)
         cpuids = zeros(Int, nt)
-        @assert length(tids_pool) == nt
         for (i, tid) in pairs(tids_pool)
             cpuids[i] = fetch(@tspawnat tid getcpuid())
         end
@@ -51,16 +44,7 @@ end
 Print the affinity masks of all Julia threads.
 """
 function print_affinity_masks(io = getstdout(); threadpool = :default, kwargs...)
-    @static if VERSION >= v"1.9-"
-        if threadpool == :all
-            tids = 1:Threads.maxthreadid()
-        else
-            tids = filter(i -> Threads.threadpool(i) == threadpool,
-                          1:Threads.maxthreadid())
-        end
-    else
-        tids = 1:nthreads()
-    end
+    tids = threadids(threadpool)
     for tid in tids
         mask = uv_thread_getaffinity(tid)
         str = _affinity_mask_to_string(mask; kwargs...)

src/threadinfo.jl

@@ -30,7 +30,7 @@ function threadinfo(io = getstdout(); blas = false, hints = false, color = true,
             end
             thread_cpuids = getcpuids(; threadpool)
         elseif threadpool == :all
-            njlthreads = Threads.maxthreadid()
+            njlthreads = Threads.nthreads(:default) + Threads.nthreads(:interactive)
             thread_cpuids = getcpuids(; threadpool = :all)
         else
             throw(ArgumentError("Unknown value for `threadpool` keyword argument. Supported " *

src/utility.jl

@@ -1,3 +1,28 @@
+function threadids(threadpool = :default)::Vector{Int}
+    @static if VERSION < v"1.9-"
+        return collect(1:nthreads())
+    else
+        if threadpool == :all
+            nt = nthreads(:default) + nthreads(:interactive)
+            tids = collect(1:Threads.maxthreadid())
+        else
+            nt = nthreads(threadpool)
+            tids = filter(i -> Threads.threadpool(i) == threadpool, 1:Threads.maxthreadid())
+        end
+
+        if nt != length(tids)
+            # IJulia manually adds a heartbeat thread that mus be ignored...
+            # see https://github.com/JuliaLang/IJulia.jl/issues/1072
+            # Currently, we just assume that it is the last thread.
+            # Might not be safe, in particular not once users can dynamically add threads
+            # in the future.
+            pop!(tids)
+        end
+
+        return tids
+    end
+end
+
 """
     @tspawnat tid -> task
 Mimics `Threads.@spawn`, but assigns the task to thread `tid` (with `sticky = true`).

test/tests_utility.jl

@@ -18,6 +18,19 @@ using Test
           [1, 5, 2, 6, 3, 7, 4, 8, 9, 10, 11, 12]
 end
 
+@testset "threadids" begin
+    @static if VERSION < v"1.9-"
+        @test ThreadPinning.threadids() == 1:Threads.nthreads()
+    else
+        @test ThreadPinning.threadids(:all) == 1:Threads.maxthreadid() # no IJulia here :)
+        # :default threads first, then :interactive threads
+        @test ThreadPinning.threadids(:default) == 1:Threads.nthreads(:default)
+        if Threads.nthreads(:interactive) > 0
+            @test ThreadPinning.threadids(:interactive) == (1:Threads.nthreads(:interactive)) .+ Threads.nthreads(:default)
+        end
+    end
+end
+
 @testset "tspawnat" begin
     @static if VERSION < v"1.9-"
         for tid in 1:Threads.nthreads()