使用NSTask和NSPipe会导致100％的CPU使用率 [英] Using NSTask and NSPipe causes 100% CPU usage

问题描述

我试图运行一个简单的bash脚本使用NSTask和直接输出到文本视图。一旦执行任务，我的应用程序的CPU使用率是100％，即使它是一个简单的 echo （现在）。

I'm trying to run a simple bash script using NSTask and direct the output to a text view. Once the task is executed, the CPU usage of my app is 100%, even though it's a simple echo (for now).

我创建了一个全新的项目来隔离问题：

I created a completely fresh project to isolate the issue:

@interface AppDelegate ()
@property (nonatomic) NSTask *task;
@property (nonatomic) NSPipe *pipe;
@end

@implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    self.pipe = [NSPipe pipe];
    self.pipe.fileHandleForReading.readabilityHandler = ^(NSFileHandle *h) {
        NSLog(@"Read: %@", [h readDataToEndOfFile]);
    };

    self.task = [[NSTask alloc] init];
    self.task.launchPath = @"/bin/bash";
    self.task.arguments = @[@"-c", @"echo test"];
    self.task.standardOutput = self.pipe;
    [self.task launch];
}
@end

它被正确执行，输出 NSLog ：

PipeTest[3933:2623] Read: <74657374 0a>

但是在我终止我的应用程序之前，CPU使用率保持在100％。

However the CPU usage stays at 100% until I terminate my app.

编辑：

时间剖面测试返回下面的列表，但我不知道如何解释This。

A Time Profiler test returns the list below, but I'm not sure how to interpret this.

>

推荐答案

文件句柄保持打开状态？

File handle left open?

@interface AppDelegate ()
@property (nonatomic) NSTask *task;
@property (nonatomic) NSPipe *pipe;
@end

@implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    self.pipe = [NSPipe pipe];
    self.pipe.fileHandleForReading.readabilityHandler = ^(NSFileHandle *h) {
        NSLog(@"Read: %@", [h readDataToEndOfFile]);
        [h closeFile];
    };

    self.task = [[NSTask alloc] init];
    self.task.launchPath = @"/bin/bash";
    self.task.arguments = @[@"-c", @"echo test"];
    self.task.standardOutput = self.pipe;
    [self.task launch];
}

关闭 NSFileHandle h 似乎会将您的CPU使用率恢复正常。

Closing the file on the NSFileHandle h seems to return your CPU usage to normal.

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