Revert "commands: Remove the rlimit tweaking on macOS"

This reverts commit bcd32f1086.

See #3582

commands/hugo.go

@@ -25,6 +25,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"sync"
 	"time"
@@ -758,6 +759,10 @@ func (c *commandeer) rebuildSites(events []fsnotify.Event) error {
 
 // newWatcher creates a new watcher to watch filesystem events.
 func (c *commandeer) newWatcher(port int) error {
+	if runtime.GOOS == "darwin" {
+		tweakLimit()
+	}
+
 	watcher, err := watcher.New(1 * time.Second)
 	var wg sync.WaitGroup
 

commands/limit_darwin.go

@@ -0,0 +1,85 @@
+// Copyright 2015 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Copyright 2015 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package commands
+
+import (
+	"syscall"
+
+	"github.com/spf13/cobra"
+	jww "github.com/spf13/jwalterweatherman"
+)
+
+func init() {
+	checkCmd.AddCommand(limit)
+}
+
+var limit = &cobra.Command{
+	Use:   "ulimit",
+	Short: "Check system ulimit settings",
+	Long: `Hugo will inspect the current ulimit settings on the system.
+This is primarily to ensure that Hugo can watch enough files on some OSs`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		var rLimit syscall.Rlimit
+		err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+		if err != nil {
+			return newSystemError("Error Getting Rlimit ", err)
+		}
+
+		jww.FEEDBACK.Println("Current rLimit:", rLimit)
+
+		jww.FEEDBACK.Println("Attempting to increase limit")
+		rLimit.Max = 999999
+		rLimit.Cur = 999999
+		err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+		if err != nil {
+			return newSystemError("Error Setting rLimit ", err)
+		}
+		err = syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+		if err != nil {
+			return newSystemError("Error Getting rLimit ", err)
+		}
+		jww.FEEDBACK.Println("rLimit after change:", rLimit)
+
+		return nil
+	},
+}
+
+func tweakLimit() {
+	var rLimit syscall.Rlimit
+	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+	if err != nil {
+		jww.ERROR.Println("Unable to obtain rLimit", err)
+	}
+	if rLimit.Cur < rLimit.Max {
+		rLimit.Max = 999999
+		rLimit.Cur = 999999
+		err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+		if err != nil {
+			jww.ERROR.Println("Unable to increase number of open files limit", err)
+		}
+	}
+}

commands/limit_others.go

@@ -0,0 +1,32 @@
+// Copyright 2015 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !darwin
+// Copyright 2015 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package commands
+
+func tweakLimit() {
+	// nothing to do
+}