从视觉上看，死锁在哪里？为什么？如何avoid/fix？
Visually where is the Deadlock? Why? How to avoid/fix?
我正在尝试理解并解决以下问题。
The following program attempts to use a pair of semaphores t and s for mutual exclusion.
Initially: s = 1, t = 0.
Thread 1 Thread 2
-------- --------
1. P(s); P(s);
2. V(s); V(s);
3. P(t); P(t);
4. V(t); V(t);
请记住：
The P operation wastes time or sleeps until a resource protected by
the semaphore becomes available, at which time the resource is
immediately claimed.
The V operation is the inverse: it makes a resource available again
after the process has finished using it.
1. Why does this program cause a deadlock?
2. What changes can be made to initial semaphore values to remove deadlock potential?
更新
根据评论，我能够更好地理解并在下面直观地说明死锁，所以如果我理解正确，请告诉我。
Here is how the deadlock happens, IF Thread 1 gets CPU Time before Thread 2:
How to fix this?
将 t 的值设置为 1
提示：您可以通过锁顺序避免死锁。例如，所有代码必须在锁定 t 之前锁定 s。这个问题演示了如果不是这种情况会发生什么。您可以 "make changes to the initial semaphore values" 以符合锁定顺序。
死锁发生在 Line 3。在这一行，Threads 都在持续等待获取资源 t 的锁。 t 的初始值为 0，这意味着它已经处于锁定状态，因此例如如果 Thread1 先到达 line 3 它会等待 t 的值变为 1 并且类似地在一段时间后 Thread2 将在同一行等待 t 变为 1。这样，两个进程将连续等待资源创建“死锁”。
我正在尝试理解并解决以下问题。
The following program attempts to use a pair of semaphores t and s for mutual exclusion.
Initially: s = 1, t = 0.
Thread 1 Thread 2
-------- --------
1. P(s); P(s);
2. V(s); V(s);
3. P(t); P(t);
4. V(t); V(t);
请记住：
The P operation wastes time or sleeps until a resource protected by the semaphore becomes available, at which time the resource is immediately claimed.
The V operation is the inverse: it makes a resource available again after the process has finished using it.
1. Why does this program cause a deadlock?
2. What changes can be made to initial semaphore values to remove deadlock potential?
更新
根据评论，我能够更好地理解并在下面直观地说明死锁，所以如果我理解正确，请告诉我。
Here is how the deadlock happens, IF Thread 1 gets CPU Time before Thread 2:
How to fix this?
将 t 的值设置为 1
提示：您可以通过锁顺序避免死锁。例如，所有代码必须在锁定 t 之前锁定 s。这个问题演示了如果不是这种情况会发生什么。您可以 "make changes to the initial semaphore values" 以符合锁定顺序。
死锁发生在 Line 3。在这一行，Threads 都在持续等待获取资源 t 的锁。 t 的初始值为 0，这意味着它已经处于锁定状态，因此例如如果 Thread1 先到达 line 3 它会等待 t 的值变为 1 并且类似地在一段时间后 Thread2 将在同一行等待 t 变为 1。这样，两个进程将连续等待资源创建“死锁”。