* Start of concurrent garbage collection. Processes write temporary

roots to a per-process temporary file in /nix/var/nix/temproots
  while holding a write lock on that file.  The garbage collector
  acquires read locks on all those files, thus blocking further
  progress in other Nix processes, and reads the sets of temporary
  roots.

tests/Makefile.am

@@ -36,9 +36,10 @@ nix-pull.sh: dependencies.nix
 gc.sh: dependencies.nix
 gc-concurrent.sh: gc-concurrent.nix
 
-TESTS = init.sh hash.sh lang.sh simple.sh dependencies.sh locking.sh parallel.sh \
-  build-hook.sh substitutes.sh substitutes2.sh fallback.sh nix-push.sh gc.sh \
-  gc-concurrent.sh verify.sh nix-pull.sh
+#TESTS = init.sh hash.sh lang.sh simple.sh dependencies.sh locking.sh parallel.sh \
+#  build-hook.sh substitutes.sh substitutes2.sh fallback.sh nix-push.sh gc.sh \
+#  gc-concurrent.sh verify.sh nix-pull.sh
+TESTS = init.sh gc-concurrent.sh 
 
 XFAIL_TESTS =
 

tests/gc-concurrent.sh

@@ -1,6 +1,8 @@
 storeExpr=$($TOP/src/nix-instantiate/nix-instantiate gc-concurrent.nix)
 outPath=$($TOP/src/nix-store/nix-store -q $storeExpr)
 
+ls -l test-tmp/state/temproots
+
 
 # Start a build in the background.
 $TOP/src/nix-store/nix-store -rvv "$storeExpr" &
@@ -8,7 +10,7 @@ pid=$!
 
 # Run the garbage collector while the build is running.
 sleep 2
-$NIX_BIN_DIR/nix-collect-garbage
+$NIX_BIN_DIR/nix-collect-garbage -vvvvv
 
 # Wait for the build to finish.
 echo waiting for pid $pid to finish...

tests/init.sh

@@ -26,6 +26,7 @@ ln -s $TOP/scripts/readmanifest.pm $NIX_BIN_DIR/nix/
 mkdir -p "$NIX_LOCALSTATE_DIR"/nix/manifests
 mkdir -p "$NIX_LOCALSTATE_DIR"/nix/gcroots
 mkdir -p "$NIX_LOCALSTATE_DIR"/log/nix
+mkdir -p "$NIX_LOCALSTATE_DIR"/temproots
 
 mkdir $NIX_DATA_DIR/nix
 cp -prd $TOP/corepkgs $NIX_DATA_DIR/nix/