document that multi-threading support is experimental

Author: Christopher Doris

docs/src/juliacall.md

@@ -140,6 +140,10 @@ be configured in two ways:
 
 ## [Multi-threading](@id py-multi-threading)
 
+!!! warning
+
+    Multi-threading support is experimental and can change without notice.
+
 From v0.9.22, JuliaCall supports multi-threading in Julia and/or Python, with some
 caveats.
 

docs/src/pythoncall.md

@@ -415,6 +415,10 @@ See [Installing Python packages](@ref python-deps).
 
 ## [Multi-threading](@id jl-multi-threading)
 
+!!! warning
+
+    Multi-threading support is experimental and can change without notice.
+
 From v0.9.22, PythonCall supports multi-threading in Julia and/or Python, with some
 caveats.
 

src/GIL/GIL.jl

@@ -4,6 +4,10 @@
 Handling the Python Global Interpreter Lock.
 
 See [`lock`](@ref), [`@lock`](@ref), [`unlock`](@ref) and [`@unlock`](@ref).
+
+!!! warning
+
+    Multi-threading support is experimental and can change without notice.
 """
 module GIL
 
@@ -32,6 +36,10 @@ threads. Since the main Julia thread holds the GIL by default, you will need to
 [`unlock`](@ref) the GIL before using this function.
 
 See [`@lock`](@ref) for the macro form.
+
+!!! warning
+
+    This function is experimental. Its semantics may be changed without notice.
 """
 function lock(f)
     state = C.PyGILState_Ensure()
@@ -52,6 +60,10 @@ threads. Since the main Julia thread holds the GIL by default, you will need to
 [`@unlock`](@ref) the GIL before using this function.
 
 The macro equivalent of [`lock`](@ref).
+
+!!! warning
+
+    This macro is experimental. Its semantics may be changed without notice.
 """
 macro lock(expr)
     quote
@@ -74,6 +86,10 @@ Python code. That other thread can be a Julia thread, which must lock the GIL us
 [`lock`](@ref).
 
 See [`@unlock`](@ref) for the macro form.
+
+!!! warning
+
+    This function is experimental. Its semantics may be changed without notice.
 """
 function unlock(f)
     state = C.PyEval_SaveThread()
@@ -94,6 +110,10 @@ Python code. That other thread can be a Julia thread, which must lock the GIL us
 [`@lock`](@ref).
 
 The macro equivalent of [`unlock`](@ref).
+
+!!! warning
+
+    This macro is experimental. Its semantics may be changed without notice.
 """
 macro unlock(expr)
     quote