From 5bd13a835b27abf4660dceb8f3de8cf62e704c11 Mon Sep 17 00:00:00 2001
From: Greg Hogan <code@greghogan.com>
Date: Wed, 3 Sep 2025 16:35:56 +0000
Subject: [PATCH] gnu: openjdk11: Disable parallel build.

* gnu/packages/java.scm (openjdk11)[arguments]
<#:parallel-build?>: Unset.
<#:phases>{build, build-jre}: Explicitly set JOBS to 1 when parallel
build unset.
(openjdk12)[arguments]<#:parallel-build?>: Set.
(openjdk9)<#:phases>{build}: Explicitly set JOBS to 1 when parallel
build is unset.

Change-Id: I1a1e5d89e6a223f069755ab7dcc6242a4e90e7cc
Signed-off-by: Julien Lepiller <julien@lepiller.eu>
---
 gnu/packages/java.scm | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/gnu/packages/java.scm b/gnu/packages/java.scm
index 4fc3ee00d46..e2dcd2d1c0d 100644
--- a/gnu/packages/java.scm
+++ b/gnu/packages/java.scm
@@ -981,7 +981,7 @@ new Date();"))
                     `(,@(if parallel-build?
                             (list (string-append "JOBS="
                                                  (number->string (parallel-job-count))))
-                            '())
+                            '("JOBS=1"))
                       ,@make-flags))))
          (add-after 'unpack 'patch-jni-libs
            ;; Hardcode dynamically loaded libraries.
@@ -1340,6 +1340,8 @@ new Date();"))
     (outputs '("out" "jdk" "doc"))
     (arguments
      (list
+      ;; Prevent a java.util.ConcurrentModificationException.
+      #:parallel-build? #f
       #:modules `((guix build gnu-build-system)
                   (guix build utils)
                   (ice-9 match)
@@ -1438,7 +1440,7 @@ new Date();"))
                      `(,@(if parallel-build?
                              (list (string-append "JOBS="
                                                   (number->string (parallel-job-count))))
-                             '())
+                             '("JOBS=1"))
                        ,@make-flags))))
           ;; jdk 11 does not build jre by default any more; so explicitly build
           ;; it (see:
@@ -1449,7 +1451,7 @@ new Date();"))
                      `(,@(if parallel-build?
                              (list (string-append "JOBS="
                                                   (number->string (parallel-job-count))))
-                             '())
+                             '("JOBS=1"))
                        ,@make-flags))))
           (replace 'install
             (lambda _
@@ -1665,6 +1667,8 @@ new Date();"))
       (patches (search-patches "openjdk-10-setsignalhandler.patch"))))
    (arguments
     (substitute-keyword-arguments (package-arguments openjdk11)
+      ;; Re-enable parallel build.
+      ((#:parallel-build? _ #t) #t)
       ((#:phases phases)
        #~(modify-phases #$phases
            #$@(if (target-aarch64?)