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Benxaomin avatar Benxaomin commented on June 9, 2024

这一块我也认为有问题,按道理来说调用phtread_cond_wait之前是需要调用pthread_mutex_lock来进行加锁的,而pthread_cond_wait调用在等待条件发生期间会阻塞线程并对mutex进行解锁操作,以避免忙等待问题;而作者最开始很明显也是加了锁的,后面不知道为什么给pthread_cond_wait的锁注释掉了,这不会导致线程安全问题和竞态条件吗?

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corn27 avatar corn27 commented on June 9, 2024

这一块我也认为有问题,按道理来说调用phtread_cond_wait之前是需要调用pthread_mutex_lock来进行加锁的,而pthread_cond_wait调用在等待条件发生期间会阻塞线程并对mutex进行解锁操作,以避免忙等待问题;而作者最开始很明显也是加了锁的,后面不知道为什么给pthread_cond_wait的锁注释掉了,这不会导致线程安全问题和竞态条件吗?

我也有同样的疑问,而且作者在庖丁解牛1中也说了要先加锁,实际代码确注释掉了,同学现在解决了这个问题嘛?

from tinywebserver.

Benxaomin avatar Benxaomin commented on June 9, 2024

这一块我也认为有问题,按道理来说调用phtread_cond_wait之前是需要调用pthread_mutex_lock来进行加锁的,而pthread_cond_wait调用在等待条件发生期间会阻塞线程并对mutex进行解锁操作,以避免忙等待问题;而作者最开始很明显也是加了锁的,后面不知道为什么给pthread_cond_wait的锁注释掉了,这不会导致线程安全问题和竞态条件吗?

我也有同样的疑问,而且作者在庖丁解牛1中也说了要先加锁,实际代码确注释掉了,同学现在解决了这个问题嘛?

嗯,我记得之前看到哪块代码调用了wait,并且那块逻辑需要加锁,为了避免在调用wait前加一次锁进入wait又加一次锁的双重锁死锁问题,所以作者把里面的锁给注释了。主要是这个普通的mutex不支持重复加锁,这一块的逻辑不是很严谨,但是应该作者为了代码易懂,所以没用高级锁

from tinywebserver.

corn27 avatar corn27 commented on June 9, 2024

这一块我也认为有问题,按道理来说调用phtread_cond_wait之前是需要调用pthread_mutex_lock来进行加锁的,而pthread_cond_wait调用在等待条件发生期间会阻塞线程并对mutex进行解锁操作,以避免忙等待问题;而作者最开始很明显也是加了锁的,后面不知道为什么给pthread_cond_wait的锁注释掉了,这不会导致线程安全问题和竞态条件吗?

我也有同样的疑问,而且作者在庖丁解牛1中也说了要先加锁,实际代码确注释掉了,同学现在解决了这个问题嘛?

嗯,我记得之前看到哪块代码调用了wait,并且那块逻辑需要加锁,为了避免在调用wait前加一次锁进入wait又加一次锁的双重锁死锁问题,所以作者把里面的锁给注释了。主要是这个普通的mutex不支持重复加锁,这一块的逻辑不是很严谨,但是应该作者为了代码易懂,所以没用高级锁

我也看到了,是这样的,多谢同学

from tinywebserver.

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