Implement a hook in base for disabling threading (#30004)

of libraries, use it to decouple Distributed from LinearAlgebra.

Author: fredrikekre

Project.toml

@@ -2,7 +2,6 @@ name = "Distributed"
 uuid = "8ba89e20-285c-5b6f-9357-94700520ee1b"
 
 [deps]
-LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Serialization = "9e88b42a-f829-5b0c-bbe9-9e923198166b"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"

src/cluster.jl

@@ -163,12 +163,6 @@ mutable struct LocalProcess
     LocalProcess() = new(1)
 end
 
-
-import LinearAlgebra
-function disable_threaded_libs()
-    LinearAlgebra.BLAS.set_num_threads(1)
-end
-
 worker_timeout() = parse(Float64, get(ENV, "JULIA_WORKER_TIMEOUT", "60.0"))
 
 

src/process_messages.jl

@@ -307,7 +307,7 @@ function handle_msg(msg::JoinPGRPMsg, header, r_stream, w_stream, version)
     topology(msg.topology)
 
     if !msg.enable_threaded_blas
-        disable_threaded_libs()
+        Base.disable_library_threading()
     end
 
     lazy = msg.lazy