From ce7242cc48bb6d1432ea7b734c14550d092818f7 Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Tue, 17 Dec 2024 20:00:26 +0000
Subject: [PATCH] precompileplkgs: release parallel limiter when waiting for
 another process (#56844)

(cherry picked from commit 37740148e1120ec833d6648dde245c0c5b79d76e)
---
 base/precompilation.jl | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/base/precompilation.jl b/base/precompilation.jl
index 95aa643e62bd2..4c9847b61090d 100644
--- a/base/precompilation.jl
+++ b/base/precompilation.jl
@@ -920,7 +920,7 @@ function _precompilepkgs(pkgs::Vector{String},
                         try
                             # allows processes to wait if another process is precompiling a given package to
                             # a functionally identical package cache (except for preferences, which may differ)
-                            t = @elapsed ret = precompile_pkgs_maybe_cachefile_lock(io, print_lock, fancyprint, pkg_config, pkgspidlocked, hascolor) do
+                            t = @elapsed ret = precompile_pkgs_maybe_cachefile_lock(io, print_lock, fancyprint, pkg_config, pkgspidlocked, hascolor, parallel_limiter) do
                                 Base.with_logger(Base.NullLogger()) do
                                     # The false here means we ignore loaded modules, so precompile for a fresh session
                                     keep_loaded_modules = false
@@ -1101,7 +1101,7 @@ function _color_string(cstr::String, col::Union{Int64, Symbol}, hascolor)
 end
 
 # Can be merged with `maybe_cachefile_lock` in loading?
-function precompile_pkgs_maybe_cachefile_lock(f, io::IO, print_lock::ReentrantLock, fancyprint::Bool, pkg_config, pkgspidlocked, hascolor)
+function precompile_pkgs_maybe_cachefile_lock(f, io::IO, print_lock::ReentrantLock, fancyprint::Bool, pkg_config, pkgspidlocked, hascolor, parallel_limiter::Base.Semaphore)
     pkg, config = pkg_config
     flags, cacheflags = config
     FileWatching = Base.loaded_modules[Base.PkgId(Base.UUID("7b1f6079-737a-58dc-b8bc-7a2ca5c1b5ee"), "FileWatching")]
@@ -1122,15 +1122,21 @@ function precompile_pkgs_maybe_cachefile_lock(f, io::IO, print_lock::ReentrantLo
         !fancyprint && lock(print_lock) do
             println(io, "    ", pkg.name, _color_string(" Being precompiled by $(pkgspidlocked[pkg_config])", Base.info_color(), hascolor))
         end
-        # wait until the lock is available
-        FileWatching.mkpidlock(pidfile; stale_age) do
-            # double-check in case the other process crashed or the lock expired
-            if Base.isprecompiled(pkg; ignore_loaded=true, flags=cacheflags) # don't use caches for this as the env state will have changed
-                return nothing # returning nothing indicates a process waited for another
-            else
-                delete!(pkgspidlocked, pkg_config)
-                return f() # precompile
-            end
+        Base.release(parallel_limiter) # release so other work can be done while waiting
+        try
+            # wait until the lock is available
+            @invokelatest Base.mkpidlock_hook(() -> begin
+                    # double-check in case the other process crashed or the lock expired
+                    if Base.isprecompiled(pkg; ignore_loaded=true, flags=cacheflags) # don't use caches for this as the env state will have changed
+                        return nothing # returning nothing indicates a process waited for another
+                    else
+                        delete!(pkgspidlocked, pkg_config)
+                        Base.acquire(f, parallel_limiter) # precompile
+                    end
+                end,
+                pidfile; stale_age)
+        finally
+            Base.acquire(parallel_limiter) # re-acquire so the outer release is balanced
         end
     end
     return cachefile