diff --git a/README.md b/README.md
index 6d5e26e..ebadcf6 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 
 ## 安装, 解压后执行
 ```shell
- Windows     ./gocron.exe web
+ Windows     gocron.exe web
  Linux、OSX  ./gocron web
 ```
 可选参数 
diff --git a/models/model.go b/models/model.go
index e1d2be1..70a7862 100644
--- a/models/model.go
+++ b/models/model.go
@@ -21,6 +21,7 @@ const (
     Enabled  Status = 1 // 启用
     Running  Status = 1 // 运行中
     Finish   Status = 2 // 完成
+    Cancel   Status = 3 // 取消
 )
 
 const (
diff --git a/models/task.go b/models/task.go
index ef86378..75649dd 100644
--- a/models/task.go
+++ b/models/task.go
@@ -22,6 +22,7 @@ type Task struct {
     Protocol TaskProtocol  `xorm:"tinyint notnull"`              // 协议 1:http 2:ssh-command 3: 系统命令
     Command  string    `xorm:"varchar(256) notnull"`             // URL地址或shell命令
     Timeout  int       `xorm:"mediumint notnull default 0"`      // 任务执行超时时间(单位秒),0不限制
+    Multi    int8      `xorm:"tinyint notnull default 1"`        // 是否允许多实例运行
     RetryTimes int8    `xorm:"tinyint notnull default 0"`         // 重试次数
     HostId   int16    `xorm:"smallint notnull default 0"`        // SSH host id，
     Remark   string    `xorm:"varchar(100) notnull default ''"`  // 备注
@@ -57,7 +58,7 @@ func (task *Task) Create() (insertId int, err error) {
 }
 
 func (task *Task) UpdateBean(id int) (int64, error)  {
-    return Db.ID(id).UseBool("status").Update(task)
+    return Db.ID(id).UseBool("status,multi").Update(task)
 }
 
 // 更新
diff --git a/models/task_log.go b/models/task_log.go
index 5200254..8371e16 100644
--- a/models/task_log.go
+++ b/models/task_log.go
@@ -21,15 +21,13 @@ type TaskLog struct {
     Hostname string       `xorm:"varchar(128) notnull defalut '' "`   // SSH主机名，逗号分隔
     StartTime time.Time `xorm:"datetime created"`                   // 开始执行时间
     EndTime   time.Time `xorm:"datetime updated"`                   // 执行完成（失败）时间
-    Status    Status    `xorm:"tinyint notnull default 1"`          // 状态 0:执行失败 1:执行中  2:执行完毕
+    Status    Status    `xorm:"tinyint notnull default 1"`          // 状态 0:执行失败 1:执行中  2:执行完毕 3:任务取消(上次任务未执行完成)
     Result    string    `xorm:"text notnull defalut '' "` // 执行结果
     TotalTime int       `xorm:"-"` // 执行总时长
     BaseModel   `xorm:"-"`
 }
 
 func (taskLog *TaskLog) Create() (insertId int64, err error) {
-    taskLog.Status = Running
-
     _, err = Db.Insert(taskLog)
     if err == nil {
         insertId = taskLog.Id
diff --git a/modules/app/app.go b/modules/app/app.go
index f4fd975..a18cb23 100644
--- a/modules/app/app.go
+++ b/modules/app/app.go
@@ -14,6 +14,7 @@ var (
     AppDir       string // 应用根目录
     ConfDir      string // 配置目录
     LogDir       string // 日志目录
+    DataDir      string // 存放session等
     AppConfig    string // 应用配置文件
     Installed    bool   // 应用是否安装过
 )
@@ -28,8 +29,9 @@ func InitEnv() {
     AppDir = wd
     ConfDir = AppDir + "/conf"
     LogDir = AppDir + "/log"
+    DataDir = AppDir + "/data"
     AppConfig = ConfDir + "/app.ini"
-    checkDirExists(ConfDir, LogDir)
+    checkDirExists(ConfDir, LogDir, DataDir)
     Installed = IsInstalled()
     if Installed {
         InitDb()
diff --git a/routers/routers.go b/routers/routers.go
index 691590e..efe33b2 100644
--- a/routers/routers.go
+++ b/routers/routers.go
@@ -105,7 +105,10 @@ func RegisterMiddleware(m *macaron.Macaron) {
         // 渲染具有缩进格式的 XML，默认为不缩进
         IndentXML: true,
     }))
-    m.Use(session.Sessioner())
+    m.Use(session.Sessioner(session.Options{
+        Provider:       "file",
+        ProviderConfig: app.DataDir + "/sessions",
+    }))
     m.Use(csrf.Csrfer())
     m.Use(toolbox.Toolboxer(m))
     checkAppInstall(m)
diff --git a/routers/task/task.go b/routers/task/task.go
index b943a4d..a9420b4 100644
--- a/routers/task/task.go
+++ b/routers/task/task.go
@@ -20,6 +20,7 @@ type TaskForm struct {
     Protocol models.TaskProtocol `binding:"In(1,2,3)"`
     Command string `binding:"Required;MaxSize(512)"`
     Timeout int `binding:"Range(0,86400)"`
+    Multi  int8 `binding:"In(1,2)"`
     RetryTimes int8
     HostId int16
     Remark string
@@ -119,10 +120,14 @@ func Store(ctx *macaron.Context, form TaskForm) string  {
     taskModel.Timeout = form.Timeout
     taskModel.Remark = form.Remark
     taskModel.Status = form.Status
+    taskModel.Multi = form.Multi
     taskModel.RetryTimes = form.RetryTimes
     if taskModel.Status != models.Enabled {
         taskModel.Status = models.Disabled
     }
+    if taskModel.Multi != 1 {
+        taskModel.Multi = 0
+    }
     taskModel.Spec = form.Spec
     if id == 0 {
         id, err = taskModel.Create()
diff --git a/service/task.go b/service/task.go
index 17070f8..2e53b75 100644
--- a/service/task.go
+++ b/service/task.go
@@ -15,6 +15,30 @@ import (
 )
 
 var Cron *cron.Cron
+var runInstance Instance
+
+// 任务ID作为Key, 不会出现并发读写, 不加锁
+type Instance struct {
+    Status map[int]bool
+}
+
+// 是否有任务处于运行中
+func (i *Instance) has(key int) bool {
+    running, ok := i.Status[key]
+    if ok && running {
+        return true
+    }
+
+    return false
+}
+
+func (i *Instance) add(key int)  {
+    i.Status[key] = true
+}
+
+func (i *Instance) done(key int)  {
+    i.Status[key] = false
+}
 
 type Task struct{}
 
@@ -28,6 +52,7 @@ type TaskResult struct {
 func (task *Task) Initialize() {
     Cron = cron.New()
     Cron.Start()
+    runInstance = Instance{make(map[int]bool)}
     taskModel := new(models.Task)
     taskList, err := taskModel.ActiveList()
     if err != nil {
@@ -159,7 +184,7 @@ func (h *SSHCommandHandler) Run(taskModel models.TaskHost) (string, error) {
 }
 
 // 创建任务日志
-func createTaskLog(taskModel models.TaskHost) (int64, error) {
+func createTaskLog(taskModel models.TaskHost, status models.Status) (int64, error) {
     taskLogModel := new(models.TaskLog)
     taskLogModel.TaskId = taskModel.Id
     taskLogModel.Name = taskModel.Task.Name
@@ -171,7 +196,7 @@ func createTaskLog(taskModel models.TaskHost) (int64, error) {
         taskLogModel.Hostname = taskModel.Alias + "-" + taskModel.Name
     }
     taskLogModel.StartTime = time.Now()
-    taskLogModel.Status = models.Running
+    taskLogModel.Status = status
     insertId, err := taskLogModel.Create()
 
     return insertId, err
@@ -202,7 +227,15 @@ func createJob(taskModel models.TaskHost) cron.FuncJob {
         return nil
     }
     taskFunc := func() {
-        taskLogId, err := createTaskLog(taskModel)
+        if taskModel.Multi == 0 && runInstance.has(taskModel.Id) {
+            createTaskLog(taskModel, models.Cancel)
+            return
+        }
+        if taskModel.Multi == 0 {
+            runInstance.add(taskModel.Id)
+            defer runInstance.done(taskModel.Id)
+        }
+        taskLogId, err := createTaskLog(taskModel, models.Running)
         if err != nil {
             logger.Error("任务开始执行#写入任务日志失败-", err)
             return
diff --git a/templates/task/index.html b/templates/task/index.html
index c24d5f5..787d2f6 100644
--- a/templates/task/index.html
+++ b/templates/task/index.html
@@ -63,6 +63,7 @@
                                <p class="sensorStatus">命令：{{{.Command}}}</p>
                                <p class="sensorStatus">超时时间：{{{if gt .Timeout 0}}}{{{.Timeout}}}秒{{{else}}}不限制{{{end}}}</p>
                                <p>重试次数: {{{.RetryTimes}}}</p>
+                               <p class="sensorStatus">是否允许多实例：{{{if gt .Multi 0}}}是{{{else}}}否{{{end}}}</p>
                                {{{if eq .Protocol 2}}}
                                <p>主机: {{{.Alias}}}</p>
                                {{{end}}}
diff --git a/templates/task/log.html b/templates/task/log.html
index 8aa7b75..ebed0a7 100644
--- a/templates/task/log.html
+++ b/templates/task/log.html
@@ -74,11 +74,13 @@
                 <td>{{{.RetryTimes}}}</td>
                 <td>{{{.Hostname}}}</td>
                 <td>
+                    {{{if ne .Status 3}}}
                     {{{if gt .TotalTime 0}}}{{{.TotalTime}}}秒{{{else}}}1秒{{{end}}}<br>
                     开始时间: {{{.StartTime.Format "2006-01-02 15:04:05" }}}<br>
                     {{{if ne .Status 1}}}
                         结束时间: {{{.EndTime.Format "2006-01-02 15:04:05" }}}
                     {{{end}}}
+                    {{{end}}}
                 </td>
                 <td>
                     {{{if eq .Status 2}}}
@@ -87,12 +89,12 @@
                         <span style="color:green">执行中</span>
                     {{{else if eq .Status 0}}}
                         <span style="color:red">失败</span>
-                    {{{else}}}
-                        <span style="color:#4499EE">待执行</span>
+                    {{{else if eq .Status 3}}}
+                        <span style="color:#4499EE">取消</span>
                     {{{end}}}
                 </td>
                 <td>
-                    {{{if ne .Status 1}}}
+                    {{{if and (ne .Status 1) (ne .Status 3)}}}
                         <button class="ui small primary button"
                                 onclick="showResult('{{{.Name}}}', '{{{.Command}}}', '{{{.Result}}}')"
                                 >查看结果
diff --git a/templates/task/task_form.html b/templates/task/task_form.html
index 5e96afc..0edcc30 100644
--- a/templates/task/task_form.html
+++ b/templates/task/task_form.html
@@ -110,6 +110,15 @@
                 <input type="text"  name="timeout"  value="{{{.Task.Timeout}}}">
             </div>
         </div>
+        <div class="three fields">
+            <div class="field">
+                <label>允许多实例运行</label>
+                <select name="multi">
+                    <option value="1"{{{if .Task}}} {{{if eq .Task.Multi 1}}}selected{{{end}}} {{{end}}}>是</option>
+                    <option value="2" {{{if .Task}}} {{{if eq .Task.Multi 0}}}selected{{{end}}} {{{end}}}>否</option>
+                </select>
+            </div>
+        </div>
         <div class="three fields">
             <div class="field">
                 <label>任务状态</label>
@@ -117,7 +126,7 @@
                     任务添加成功后，是否立即调度
                 </div>
                 <select name="status">
-                    <option value="2"{{{if .Task}}} {{{if eq .Task.Status 2}}}selected{{{end}}} {{{end}}}>暂停</option>
+                    <option value="2"{{{if .Task}}} {{{if eq .Task.Status 0}}}selected{{{end}}} {{{end}}}>暂停</option>
                     <option value="1" {{{if .Task}}} {{{if eq .Task.Status 1}}}selected{{{end}}} {{{end}}}>激活</option>
                 </select>
             </div>