add GC.safepoint() for compute-bound threads (#33092)

Author: JeffBezanson

base/gcutils.jl

@@ -94,4 +94,19 @@ macro preserve(args...)
     end)
 end
 
+"""
+    GC.safepoint()
+
+Inserts a point in the program where garbage collection may run.
+This can be useful in rare cases in multi-threaded programs where some threads
+are allocating memory (and hence may need to run GC) but other threads are doing
+only simple operations (no allocation, task switches, or I/O).
+Calling this function periodically in non-allocating threads allows garbage
+collection to run.
+
+!!! compat "Julia 1.4"
+    This function is available as of Julia 1.4.
+"""
+safepoint() = ccall(:jl_gc_safepoint, Cvoid, ())
+
 end # module GC

doc/src/base/base.md

@@ -395,6 +395,7 @@ Base.functionloc(::Method)
 Base.GC.gc
 Base.GC.enable
 Base.GC.@preserve
+Base.GC.safepoint
 Meta.lower
 Meta.@lower
 Meta.parse(::AbstractString, ::Int)