Adding process lock for bundle install operations to fix issue where multiple concurrent bundle install operations fail to complete

4 files changed, 60 insertions, 14 deletions

diff --git a/lib/bundler.rb b/lib/bundler.rb
index b0f6869423..9baa5fd788 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -40,6 +40,7 @@ module Bundler
   autoload :LazySpecification,      "bundler/lazy_specification"
   autoload :LockfileParser,         "bundler/lockfile_parser"
   autoload :MatchPlatform,          "bundler/match_platform"
+  autoload :ProcessLock,            "bundler/process_lock"
   autoload :RemoteSpecification,    "bundler/remote_specification"
   autoload :Resolver,               "bundler/resolver"
   autoload :Retry,                  "bundler/retry"
diff --git a/lib/bundler/installer.rb b/lib/bundler/installer.rb
index 78a73eeedd..cbd5b6ec20 100644
--- a/lib/bundler/installer.rb
+++ b/lib/bundler/installer.rb
@@ -68,23 +68,25 @@ module Bundler
     def run(options)
       create_bundle_path
 
-      if Bundler.settings[:frozen]
-        @definition.ensure_equivalent_gemfile_and_lockfile(options[:deployment])
-      end
+      ProcessLock.lock do
+        if Bundler.settings[:frozen]
+          @definition.ensure_equivalent_gemfile_and_lockfile(options[:deployment])
+        end
 
-      if @definition.dependencies.empty?
-        Bundler.ui.warn "The Gemfile specifies no dependencies"
-        lock
-        return
-      end
+        if @definition.dependencies.empty?
+          Bundler.ui.warn "The Gemfile specifies no dependencies"
+          lock
+          return
+        end
 
-      resolve_if_needed(options)
-      ensure_specs_are_compatible!
-      warn_on_incompatible_bundler_deps
-      install(options)
+        resolve_if_needed(options)
+        ensure_specs_are_compatible!
+        warn_on_incompatible_bundler_deps
+        install(options)
 
-      lock unless Bundler.settings[:frozen]
-      Standalone.new(options[:standalone], @definition).generate if options[:standalone]
+        lock unless Bundler.settings[:frozen]
+        Standalone.new(options[:standalone], @definition).generate if options[:standalone]
+      end
     end
 
     def generate_bundler_executable_stubs(spec, options = {})
diff --git a/lib/bundler/process_lock.rb b/lib/bundler/process_lock.rb
new file mode 100644
index 0000000000..3f848fe516
--- /dev/null
+++ b/lib/bundler/process_lock.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module Bundler
+  class ProcessLock
+    def self.lock(bundle_path = Bundler.bundle_path)
+      lock_file_path = File.join(bundle_path, "bundler.lock")
+
+      File.open(lock_file_path, "w") do |f|
+        f.flock(File::LOCK_EX)
+
+        yield
+      end
+    rescue Errno::ENOLCK # NFS
+      raise if Thread.main != Thread.current
+
+      yield
+    ensure
+      File.delete(lock_file_path) if File.exist?(lock_file_path)
+    end
+  end
+end
diff --git a/spec/install/process_lock_spec.rb b/spec/install/process_lock_spec.rb
new file mode 100644
index 0000000000..113fd37934
--- /dev/null
+++ b/spec/install/process_lock_spec.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+RSpec.describe "process lock spec" do
+  describe "when an install operation is already holding a process lock" do
+    it "will not run a second concurrent bundle install until the lock is released" do
+      thread = Thread.new do
+        Bundler::ProcessLock.lock(default_bundle_path) do
+          sleep 1 # ignore quality_spec
+          expect(the_bundle).not_to include_gems "rack 1.0"
+        end
+      end
+
+      install_gemfile! <<-G
+        source "file://#{gem_repo1}"
+        gem "rack"
+      G
+
+      thread.join
+      expect(the_bundle).to include_gems "rack 1.0"
+    end
+  end
+end