使用NSTask和NSPipe会导致100%的CPU使用率

Question

我正在尝试使用NSTask运行一个简单的bash脚本并将输出定向到文本视图.执行任务后,我的应用程序的CPU使用率为100%,即使它很简单echo(暂时).

我创建了一个全新的项目来隔离问题:

@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

它被正确执行并输出(作为NSData)记录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%.

编辑:

Time Profiler测试返回下面的列表,但我不知道如何解释这个.

Answer 1

文件句柄是否打开？

@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];
}

关闭文件NSFileHandle h似乎会使您的CPU使用率恢复正常.