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Asked: 2026-05-30T08:13:29+00:00

I want to implement a mutex lock. From my understanding, mutex.lock() should work like

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I want to implement a mutex lock.
From my understanding, mutex.lock() should work like
1) check lock owner
2) if lock is owned, put thread in waiting queue
3) suspend this thread until another thread send a wait up signal

However, there is nothing like pthread_suspend(), then how do I do suspend?
I found someone saying use pthread_con_wait(), but seems if I want to use that function, I have to set up a pthread_mutex lock first, which it doesn’t make sense to use pthread_mutex inside my mutex.

Well, if my understanding of mutex is wrong, please correct me.

Thanks.

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  1. Editorial Team

    mutex.lock() should work like:

    1) check lock owner
    2) if lock is owned, put thread in waiting queue
    3) suspend this thread until THE THREAD THAT OWNS THE LOCK sends a wake up signal. No other thread can release the lock.

    These steps should be performed as an atomic operation so that the correct behaviour is followed for all threads acquiring/releasing the mutex, no matter how such calls may be interrupted and reentered from other threads.

    ‘However, there is nothing like pthread_suspend(), then how do I do suspend?’ – usually, you don’t. The OS kernel provides synchronization primitives that can block threads that should not run on. To implement a ‘suspend’ in user-space, you can only spin-wait – something that is a good strategy in a few cases, (underloaded multi-core box where the lock is only held for a very short time), but certainly not all, (and can lead to spectacularly disastrous livelocks across whole clusters of machines).

    If you want a mutex, use an OS mutex – that’s what any cross-platform lib. will do.

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